半导体所最新SCI论文（2019.07.25--08.08） [2019-08-09] |
| 8月8日：
Record 1 of 16
Authors: Wang, YM; Yu, JL; Zeng, XL; Chen, YH;Liu, Y; Cheng, SY; Lai, YF; Yin, CM; He, K; Xue, QK JOURNAL OF PHYSICS-CONDENSED MATTER Volume: 31 Issue: 41 Published: OCT16 2019 Language: English Documenttype: Article Abstract: The circular (CPGE) and linear photogalvanic effect(LPGE) of a three-dimensional topological insulator Bi(2)Se(3 )thin film ofseven quintuple layers excited by near-infrared (1064 nm) and mid-infrared(10.6 mu m) radiations have been investigated. The comparison of the CPGEcurrent measured parallel and perpendicular to the incident plane, togetherwith the comparison of the CPGE current under front and back illuminations,indicates that the CPGE tinder front illumination of 1064nm light is dominatedby the top surface states of the Bi(2)Se(3 )thin film. The CPGE current excitedby 10.6 mu m light is about one order larger than that excited by 1064nm light,which may be attributed to the smaller cancelation effect of the CPGE generatedin the two-dimensional electron gas when excited by 10.6 mu m on light. Underthe excitation of 1064nm light, the LPGE current is dominated by the componentwhich shows an even parity of incident angles, while the I,PGE current excitedby 10.6 mu m light is mainly contributed by the component which is an oddparity of incident angles. Both of the CPGE and LPGE currents excited by 1064nmdecrease with increasing temperature, which may be owing to the decrease of themomentum relaxation time and the stronger electron-electron scattering withincreasing temperature, respectively.
Record 2 of 16
Authors: Mao, SW; Lu, J; Wang, HL; Zhao, XP; Wei,DH; Zhao, JH JOURNAL OF PHYSICS D-APPLIED PHYSICS Volume: 52 Issue: 40 Published: OCT2 2019 Language: English Documenttype: Article Abstract: We report on the tunneling magnetoresistance (TMR) effectin fully perpendicular magnetic tunnel junctions (p-MTJs) with the corestructure of L1(0)-MnAl/MgO/Co2MnSi/MnAl. The multilayer is epitaxially grownon GaAs (0 0 1) substrate by molecular-beam epitaxy (MBE), and both the top andbottom MnAl layers show well perpendicular magnetic anisotropy (PMA).Meanwhile, an inverse TMR effect with the MR ratio of 10% is observed at 5 K,which is attributed to the intrinsic negative spin polarization of MnAl incontrast to the positive one in Co2MnSi. This work proposes a MnAl-based fullyp-MTJ for future STT-MRAM applications.
Record 3 of 16
Authors: Wu, JX; Chen, JZ; Jiang, XW JOURNAL OF PHYSICS D-APPLIED PHYSICS Volume: 52 Issue: 39 Published: SEP25 2019 Language: English Documenttype: Article Abstract: Multiscale simulation combining density functional theoryof defect physics and charge transport calculation is carried out to understandthe intrinsic mechanism of the lateral charge loss in silicon nitride(Si3N4)-based 3D NAND flash memory. In this work, the defects' structures,trapping centers, and trap levels are investigated by ab initio calculations.Wherein, the focus is put on the nitrogen vacancy (V-N), puckered nitrogenvacancy (VNP) and H-/O-incorporation. It shows that the VNP and O atom willintroduce extremely shallow electron traps which can be eliminated by the Hpassivation. The stability of several kinds of defects is also studied. To shednew light on the impact of trap levels on the charge de-trapping and thelateral charge loss, numerical simulations are performed with thedrift-diffusion model and Poole-Frenkel model.
Record 4 of 16 Flexible picosecond burst generation in a mode-lockedNd:YVO4 laser with a compound cavity
Authors: He, CJ; Yu, HJ; Zhang, JY; Zou, SZ;Zhao, PF; Lin, XC APPLIED PHYSICS B-LASERS AND OPTICS Volume: 125 Issue: 8 Published: AUG2019 Language: English Documenttype: Article DOI: 10.1007/s00340-019-7256-2 Abstract: We present the generation of picosecond bursts withcontrollable pulse number in a passively mode-locked Nd:YVO4 laser with acompound cavity. This is the first time to use a compound cavity withadditional SESAM to generate pulse burst. The device is constructed byinserting an HWP in the cavity, which reflects part of light in the main cavityinto the auxiliary cavity and then the reflected beam is sent back after adelay in the auxiliary cavity. By controlling the power reflected into the maincavity from the auxiliary cavity, a series of bursts can be created with aselectable pulse number and adjustable temporal separation between the pulses.The temporal separation between two adjacent picosecond pulses in the burst canbe adjusted by changing the length difference between two cavities. Thetemporal width of the burst can be adjusted from picosecond to nanosecond, andthe repetition rate of the burst is the same as that in continuous wavemode-locked laser. The generation of the burst is presumably attributed to thetemporal addition of laser pulses from the two cavities. This work provides auseful method for generating controllable picosecond laser burst.
Record 5 of 16
Authors: Zhang, XB; Li, C; Jiao, YQ; Tangdiongga,E; Liu, Y; Cao, ZZ; Koonen, T JOURNAL OF LIGHTWAVE TECHNOLOGY Volume: 37 Issue: 15 Pages: 3713-3720 Published: AUG1 2019 Language: English Documenttype: Article Abstract: In this paper, a crosstalk-mitigated transmission schemein arrayed waveguide grating router (AWGR) based two dimensional infraredbeam-steered optical wireless communication (OWC) system is proposed for indoorapplications. By creating polarization orthogonality between the odd and evenAWGR channels, high crosstalk tolerance between spectrally overlapping AWGRchannels is realized experimentally. Because two signals with orthogonalpolarization states will not beat with each other in a photodiode. The opticalcrosstalk on the orthogonal polarization state will not generate a heat noteupon detection and thus crosstalk in the electrical domain can be largelyreduced. Reduced crosstalk leads to a reduction in the required spectral guardband and/or an improved tolerance to spectral overlap, which allows higherspectral efficiency. Moreover, the port number of an AWGR can be increased bysimply shortening the spatial gap between adjacent output waveguides on a chip.The higher port number can support the high spatial resolution of the steeredOWC system. This technique can also tolerate the wavelength misalignmentbetween AWGRs and lasers, which relaxes the design of low crosstalk AWGRs andhigh wavelength stable lasers. A 20 Gbit/s data rate, four-level pulse amplitudemodulation OWC transmission has been experimentally demonstrated over 1.2-mfree-space link. The experimental results show that the proposed scheme canmaintain stable, low crosstalk impact with an apparent improvement of theresponsivity.
Record 6 of 16
Authors: Pan, GZ; Xu, C; Xie, YY; Dong, YB; Wang,QH; Deng, J; Xun, M; Chen, HD JAPANESE JOURNAL OF APPLIED PHYSICS Volume: 58 Issue: 8 Published: AUG1 2019 Language: English Documenttype: Article Abstract: Micro electronically controlled liquid crystal opticalphase modulators (LCOPMs) are on-chip integrated with partially coherent verticalcavity surface emitting laser (VCSEL) array to improve the array's beam qualityand optical intensity. The initial phase shift among array elements introducedby imperfect fabrication is compensated by adjusting the voltages loaded on theLCOPMs. Experimental results show that the beamwidth of the VCSEL array isreduced by 28% and the intensity ratio of the central lobe to the secondarylobe in the far-field is increased by 50% after phase compensation by theLCOPMs. (C) 2019 The Japan Society of Applied Physics
Record 7 of 16
Authors: Zhang, CX; Turyanska, L; Cao, HC; Zhao,LX; Fay, MW; Temperton, R; O'Shea, J; Thomas, NR; Wang, KY; Luan, WL; Patane, A NANOSCALE Volume: 11 Issue: 28 Pages: 13450-13457 Published: JUL28 2019 Language: English Documenttype: Article DOI: 10.1039/c9nr03707a Abstract: Despite important advances in the synthesis of inorganicperovskite nanocrystals (NCs), the long-term instability and degradation oftheir quantum yield (QY) over time need to be addressed to enable the furtherdevelopment and exploitation of these nanomaterials. Here we report stableCsPbI3 perovskite NCs and their use in hybrid light emitting diodes (LEDs),which combine in one system the NCs and a blue GaN-based LED. Nanocrystals withimproved morphological and optical properties are obtained by optimizing thepost-synthesis replacement of oleic acid ligands with iminodibenzoic acid: theNCs have a long shelf-life (>2 months), stability under differentenvironmental conditions, and a high QY, of up to 90%, in the visible spectralrange. Ligand replacement enables the engineering of the morphological andoptical properties of the NCs. Furthermore, the NCs can be used to coat thesurface of a GaN-LED to realize a stable diode where they are excited by bluelight from the LED under low current injection conditions, resulting inemissions at distinct wavelengths in the visible range. The high QY andfluorescence lifetime in the nanosecond range are key parameters for visiblelight communication, an emerging technology that requires high-performancevisible light sources for secure, fast energy-efficient wireless transmission.
Record 8 of 16
Authors: Gao, W; Zheng, ZQ; Li, YT; Zhao, Y; Xu,L; Deng, HX; Li, JB NANOSCALE Volume: 11 Issue: 28 Pages: 13309-13317 Published: JUL28 2019 Language: English Documenttype: Article DOI: 10.1039/c9nr01966a Abstract: In recent years, with the rapid development of transfertechnologies related to graphene and other two-dimensional layered materials(2DLMs), graphene sandwiched 2DLMs have been confirmed to be outstandingtunneling and optoelectronic devices. Here, compared to the planar SnSe2-Audevice, the SnSe2 device with different thicknesses (12-256 nm) is incorporatedinto graphene sandwiched structures for photodetection. The results indicatethat the photoresponse properties are dependent on the thickness and gatevoltage. In particular, under 532 nm illumination and at a V-g of +80 V, theSnSe2 device with a thickness of 96.5 nm shows an impressively high responsivityof 1.3 x 10(3) A W-1, an external quantum efficiency of 3 x 10(5)%, and adetectivity of 1.2 x 10(12) Jones. Besides, a high response speed (a rise timeof 30.2 ms and a decay time of 27.2 ms) and flat photoswitching behavior areachieved without the gate voltage. In addition, the intrinsic mechanisms arefurther discussed through the relative spatial potential difference and theband alignment diagrams of the graphene-SnSe2-graphene and Au-SnSe2-Austructures. These findings indicate that SnSe2 has great potential forpractical applications in next generation high performance optoelectronics.
Record 9 of 16 Microfiber coupler with a Sagnac loop for water pollutiondetection
Authors: Zu, LJ; Zhang, HM; Miao, YP; Li, B; Yao,JQ APPLIED OPTICS Volume: 58 Issue: 21 Pages: 5859-5864 Published: JUL20 2019 Language: English Documenttype: Article DOI: 10.1364/AO.58.005859 Abstract: The measurement of chloride ion concentrations has beenstudied for the purpose of monitoring the quality of water resources. In thispaper, a chloride ion sensor based on a microfiber coupler with a Sagnac loopis proposed. The microfiber coupler, which acts as the sensing unit and has adiameter of 10 mu m and a length of 1 mm, is fabricated using theflame-brushing technique, and the two ends are connected to form a Sagnac loop,which acts as a reflector to enhance the reflection in the structure.Experimental results show that the sensitivity reaches a maximum of 423pm/parts per thousand and that the detection limit for the chloride ionconcentration is 0.447 parts per thousand at a wavelength of 1595 nm. Theproposed sensor is characterized by a simple and easy manufacturing process,compact structure, and low cost; further, this sensing unit has great potentialfor applications in marine chloride detection and environmental safetymonitoring, especially for monitoring building corrosion and water pollution.(C) 2019 Optical Society of America
Record 10 of 16 Design Principles of p-Type Transparent ConductiveMaterials
Authors: Cao, RY; Deng, HX; Luo, JW ACS APPLIED MATERIALS & INTERFACES Volume: 11 Issue: 28 Pages: 24837-24849 Published: JUL17 2019 Language: English Documenttype: Article Abstract: Transparent conductive materials (TCMs) has always beenplaying a significant role in electronic and photovoltaic area, due to itsprominent optical and electronic properties. To render those transparentmaterials highly conductive, efficient n- and p- type doping is criticallyneeded to obtain high concentration of free electron and hole carriers. Despiteextensive research over the past five decades, high quality p-type doping ofwide-band-gap transparent materials remains a challenge. Here, we summarizefour proposed design principles to enhance the p-type conductivity of thesewide band gap materials, including (i) reducing the formation energy of theacceptors to enhance the dopant concentration; (u) lowering the ionizationenergy and, hence, increasing the ionization of the acceptors to increase theconcentration of the free holes; (iii) increasing the VBM of the host materialto approaching the pinned Fermi level; and (iv) suppressing the compensatingdonors to shifting the pinning Fermi level toward the VBM. For each mechanism, wediscuss in detail its underlying physics and provided some examples toillustrate the design principles. From this review, one could learn the dopingprinciples and have a strategic mind when designing other p-type materials.
Record 11 of 16
Authors: Wang, JZ; Senanayak, SP; Liu, J; Hu, YY;Shi, YJ; Li, ZL; Zhang, CX; Yang, BY; Jiang, LF; Di, DW; Ievlev, AV;Ovchinnikova, OS; Ding, T; Deng, HX; Tang, LM; Guo, YL; Wang, JP; Xiao, K;Venkateshvaran, D; Jiang, L; Zhu, DB; Sirringhaus, HN ADVANCED MATERIALS
Abstract: Optoelectronic devices based on metal halide perovskites,including solar cells and light-emitting diodes, have attracted tremendousresearch attention globally in the last decade. Due to their potential toachieve high carrier mobilities, organic-inorganic hybrid perovskite materialscan enable high-performance, solution-processed field-effect transistors (FETs)for next-generation, low-cost, flexible electronic circuits and displays.However, the performance of perovskite FETs is hampered predominantly by deviceinstabilities, whose origin remains poorly understood. Here, perovskitesingle-crystal FETs based on methylammonium lead bromide are studied and deviceinstabilities due to electrochemical reactions at the interface between theperovskite and gold source-drain top contacts are investigated. Despite formingthe contacts by a gentle, soft lamination method, evidence is found that evenat such "ideal" interfaces, a defective, intermixed layer is formedat the interface upon biasing of the device. Using a bottom-contact, bottom-gatearchitecture, it is shown that it is possible to minimize such a reactionthrough a chemical modification of the electrodes, and this enables fabricationof perovskite single-crystal FETs with high mobility of up to approximate to 375px(2) V-1 s(-1) at 80 K. This work addresses one of the key challenges towardthe realization of high-performance solution-processed perovskite FETs.
Record 12 of 16 Semiconductor-metal transition in GaAs nanowires underhigh pressure
Authors: Liang, YL; Yao, Z; Yin, XT; Wang, P; Li,LX; Pan, D; Li, HY; Li, QJ; Liu, BB; Zhao, JH CHINESE PHYSICS B Volume: 28 Issue: 7 Published: JUL2019 Language: English Documenttype: Article DOI: 10.1088/1674-1056/28/7/076401 Abstract: We investigate the structural phase transitions andelectronic properties of GaAs nanowires under high pressure by usingsynchrotron x-ray diffraction and infrared reflectance spectroscopy methods upto 26.2 GPa at room temperature. The zinc-blende to orthorhombic phasetransition was observed at around 20.0 GPa. In the same pressure range,pressure-induced metallization of GaAs nanowires was confirmed by infraredreflectance spectra. The metallization originates from the zinc-blende toorthorhombic phase transition. Decompression results demonstrated that thephase transition from zinc-blende to orthorhombic and the pressure-inducedmetallization are reversible. Compared to bulk materials, GaAs nanowires showlarger bulk modulus and enhanced transition pressure due to the size effectsand high surface energy.
Record 13 of 16 Multi-functional optical fiber sensor system based on adense wavelength division multiplexer
Authors: Yin, YX; Wu, ZF; Sun, SW; Tian, L; Wang,XB; Wu, YD; Zhang, DM CHINESE PHYSICS B Volume: 28 Issue: 7 Published: JUL2019 Language: English Documenttype: Article DOI: 10.1088/1674-1056/28/7/074202 Abstract: We propose a novel and efficient multi-functional opticalfiber sensor system based on a dense wavelength division multiplexer (DWDM).This system consists of an optical fiber temperature sensor, an optical fiberstrain sensor, and a 48-channel DWDM. This system can monitor temperature andstrain changes at the same time. The ranges of these two sensors are from -20degrees C to 100 degrees C and from -1000 mu epsilon to 2000 mu epsilon,respectively. The sensitivities of the temperature sensor and strain sensor are0.03572 nm/degrees C and 0.03808 nm/N, respectively. With the aid of abroadband source and spectrometer, different kinds and ranges of parameters inthe environment can be monitored by using suitable sensors.
Record 14 of 16
Authors: Hao, HM; Su, XB; Zhang, J; Ni, HQ; Niu,ZC CHINESE PHYSICS B Volume: 28 Issue: 7 Published: JUL2019 Language: English Documenttype: Article DOI: 10.1088/1674-1056/28/7/078104 Abstract: Systematic investigation of InAs quantum dot (QD) growthusing molecular beam epitaxy has been carried out, focusing mainly on the InAsgrowth rate and its effects on the quality of the InAs/GaAs quantum dots. Byoptimizing the growth rate, high quality InAs/GaAs quantum dots have beenachieved. The areal quantum dot density is 5.9 x 10(10) cm(-2), almost doublethe conventional density (3.0 x 10(10) cm(-2)). Meanwhile, the linewidth isreduced to 29 meV at room temperature without changing the areal dot density.These improved QDs are of great significance for fabricating high performancequantum dot lasers on various substrates.
Record 15 of 16 Tuning a Binary Ferromagnet into a Multistate Synapsewith Spin-Orbit-Torque-Induced Plasticity
Authors: Cao, Y; Rushforth, AW; Sheng, Y; Zheng,HZ; Wang, KY ADVANCED FUNCTIONAL MATERIALS Volume: 29 Issue: 25 Published: JUN2019 Language: English Documenttype: Article Abstract: Ferromagnets with binary states are limited forapplications as artificial synapses for neuromorphic computing. Here, it isshown how synaptic plasticity of a perpendicular ferromagnetic layer (FM1) canbe obtained when it is interlayer exchange-coupled by another in-planeferromagnetic layer (FM2), where a magnetic field-free current-drivenmultistate magnetization switching of FM1 in the Pt/FM1/Ta/FM2 structure is inducedby spin-orbit torque. Current pulses are used to set the perpendicularmagnetization state, which acts as the synapse weight, and spintronicimplementation of the excitatory/inhibitory postsynaptic potentials and spiketiming-dependent plasticity are demonstrated. This functionality is madepossible by the action of the in-plane interlayer exchange coupling field whichleads to broadened, multistate magnetic reversal characteristics. Numericalsimulations, combined with investigations of a reference sample with a singleperpendicular magnetized Pt/FM1/Ta structure, reveal that the broadening is dueto the in-plane field component tuning the efficiency of the spin-orbit torqueto drive domain walls across a landscape of varying pinning potentials. The conventionallybinary FM1 inside the Pt/FM1/Ta/FM2 structure with an inherent in-planecoupling field is therefore tuned into a multistate perpendicular ferromagnetand represents a synaptic emulator for neuromorphic computing, demonstrating asignificant pathway toward a combination of spintronics and synapticelectronics.
Record 16 of 16 Exploration on hold-off capacity of high powerrepetitively acousto-optic Q-switched Nd:YAG rod laser
Authors: Wang, YB; Zhang, ZY; Liang, H; Gao, JC;Qu, SC; Lin, XC OPTIK Volume: 185 Pages: 161-167 Published: 2019 Language: English Documenttype: Article DOI: 10.1016/j.ijleo.2019.03.113 Abstract: The hold-off capacity of high-power repetitivelyacousto-optic Q-switched Nd:YAG rod laser with different placement methods inthe flat-flat cavity is explored in detail. Five types of typical placement areillustrated and it is confirmed that two orthogonally placed longitudinal waveQ-switches which are placed at the larger beam width in the laser cavity havebetter performance than others in terms of the theory, simulation andexperiment. An average power of 408 W along with 79 ns pulse width at 15 kHz isobtained with 12.98% electro-to-optical efficiency and 344 kW peak power.
8月1日：
Record 1 of 10
Authors: Wang, P; Xia, JB; Wu, HB JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Volume: 490 Published: NOV15 2019 Language: English Documenttype: Article DOI: 10.1016/j.jmmm.2019.165490 Abstract: We have systematically investigated the electronicstructures, magnetic properties and strain effects of quaternary Heuslercompounds FeMnCrZ (Z = P, As, Sb, Bi, Se, Te) by using the self-consistentfull-potential linearized-augmented plane-wave (FPLAPW) method with thegeneralized gradient approximation (GGA) and the local density approximation(LDA) + U methods based on the density functional theory (DFT). By analyzingthe electronic structures of these six compounds within GGA, we have found thatthe FeMnCrAs, FeMnCrSb, and FeMnCrTe alloys show excellent half-metallicferrimagnetism, and the FeMnCrP and FeMnCrBi compounds present nearhalf-metallicity. By using the LDA + U method, we found that FeMnCrP, FeMnCrAsand FeMnCrTe are half-metals. The total spin magnetic moments for all thehalf-metals satisfy the Slater-Pauling 24 electron-rule, confirming theexistence of the half-metallic gap. The estimated Curie temperatures of allcompounds exceed the room temperature, making the half-metal compoundspromising for spintronic applications. Finally, the effects of uniform andtetragonal strain have been investigated. The half-metallicity can be eitherenhanced, reduced or destroyed by a uniform strain. A ferrimagnetism toferromagnetism phase transition can be induced by a uniform lattice expansionwithin the LDA + U method. The effects of the tetragonal distortion turn out tobe negligible for these compounds.
Record 2 of 10 Excellent Gas Sensing of CdS Nanowires Decorated with AgNanoparticles
Authors: Zhang, N; Ma, XH; Ruan, SP; Yin, YY; Li,CN; Zhang, HF; Chen, Y JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY Volume: 19 Issue: 11 Pages: 7083-7088 Published: NOV2019 Language: English Documenttype: Article Abstract: In this study, CdS nanowires (NWs)/Ag nanoparticlematerials (CdS@Ag) with Schottky junction were synthesized by a simple process.The Ag nanoparticles with a diameter of 3-10 nm were uniformly scattered on thesurface of CdS NWs with an average diameter of 30 nm. The gas sensingproperties and the effect of Ag content and relative humidity on the ethanolsensing properties of CdS NWs were investigated in detail. When the relativehumidity was below 60% RH, the sensor, especially the one based on CdS@Ag0.1,exhibited an enhanced ethanol sensing response and selectivity compared withthat of pristine CdS NWs, which was believed that Ag catalyzed the reactionbetween ionized oxygen species and ethanol. However, excessive Ag content doesnot mean a higher response and even decreased the response. Also, the stabilityof CdS NWs and CdS@Ag NWs was also investigated, which were almost stable forfour months.
Record 3 of 10
Authors: Yan, HW; Liu, Q; Cui, X; Shen, XF; Hu,PF; Liu, WL; Ge, YW; Zhang, L; Liu, LL; Song, CB; Liu, Y AQUACULTURE RESEARCH Volume: 50 Issue: 8 Pages: 2066-2080 Published: AUG2019 Language: English Documenttype: Article DOI: 10.1111/are.14073 Abstract: We assessed the effects of light intensity and spectrumon the growth, development and survival of Dicentrarchus labrax larvae from 30to 96 days after hatching. Twelve lighting regimes were applied using 0.3, 1and 2 W/m(2) full spectrum white, blue, red and green light. By day 66 ofexposure, growth performance was significantly better in larvae reared undergreen or red light compared with white or blue light (p < 0.05), while itwas significantly better at 2.0 W/m(2) compared with 1.0 or 0.3 W/m(2) (p <0.05). Larvae reared under white or blue light had significantly moredeformities (p < 0.05) than did larvae reared under light of other spectra,while larvae reared under 0.3 W/m(2) light intensity had a significantly higherproportion of jaw malformations than reared under 1.0 and 2.0 W/m(2) (p <0.05). Dicentrarchus labrax larvae subjected to green light showed significantlylower survival compared with the other light spectra (p < 0.05). Moreover,light significantly affected brain aanat1a, aanatt1b, mellc, mt1, mt2, gh, tshand crf mRNA expression. Therefore, the red and green light groups (or under2.0 W/m(2)) could improve the growth performance and enhance secretion ofmelatonin, gh and tsh, and reduce the proportion of jaw malformations.
Record 4 of 10
Authors: Yang, H; Pan, LF; Wang, XT; Deng, HX;Zhong, MZ; Zhou, ZQ; Lou, Z; Shen, GZ; Wei, ZM ADVANCED FUNCTIONAL MATERIALS
Abstract: Mixed-valence states can bring unexpected uniquephenomena, especially novel anisotropic physics, due to structural asymmetry,which originate from the discrepant distribution of atoms with differentvalence. This study reports an unexploited mixed-valence-driven quasi-1D (SnSnS3)-Sn-II-S-IVcrystal, which exhibits widely and distinctively anisotropic polarized-lightabsorption reaching approximate to 3.4 from the deep ultraviolet tonear-infrared region (250-850 nm). The fabricated polarization-sensitivephotodetectors based on highly air-stable (SnSnS3)-Sn-II-S-IV nanowires displaystrong linear dichroism among the UV-vis-NIR spectrum with responsivityexceeding approximate to 150 A W-1. Furthermore, the devices are furtherconstructed onto a flexible polyethylene terephthalate (PET) substrate and thephotoresponse remains roughly unchanged after repeated bending. This work basedon novel mixed-valence-driven quasi-1D ternary sulfide (SnSnS3)-Sn-II-S-IVexcites interest in low-symmetry semiconductors for developing broadly spectralpolarization-sensitive photodetectors with environmental stability andmechanical flexibility.
Record 5 of 10
Authors: Li, R; Zhang, RM; Lou, Z; Huang, TT;Jiang, K; Chen, D; Shen, GZ NANOSCALE Volume: 11 Issue: 25 Pages: 12116-12123 Published: JUL7 2019 Language: English Documenttype: Article DOI: 10.1039/c9nr03641e Abstract: Metal germanate nanospheres including Ca2Ge7O16, Zn2GeO4and SrGe4O9 were successfully synthesized by a direct and large-scaleelectrospraying method. As anodes for lithium ion batteries, the prepared metalgermanate nanospheres showed high electrochemical lithium storage performance includingexcellent cycling stability and high rate capacity. Especially, the Ca2Ge7O16nanosphere anode delivered a high specific capacity of similar to 670 mA hg(-1) at 0.2 A g(-1). The capacity retention was maintained around 71% evenafter 500 cycles. Moreover, when applied as room-temperature ammonia gassensors, all three prepared germinate nanospheres showed significant sensingresponse values (6.04 for SrGe4O9, 2.73 for Zn2GeO4 and 1.70 for Ca2Ge7O16),fast response-recovery time, excellent stability and outstanding selectivity.
Record 6 of 10
Authors: Xue, XD; Liu, Y; Zhu, LP; Huang, W;Zhang, Y; Zeng, XL; Wu, J; Xu, B; Wang, ZG; Chen, YH; Zhang, WF CHINESE PHYSICS LETTERS Volume: 36 Issue: 7 Published: JUL2019 Language: English Documenttype: Article DOI: 10.1088/0256-307X/36/7/077201 Abstract: The spin-polarized photocurrent is used to study thein-plane electric field dependent spin transport in undoped InGaAs/AlGaAsmultiple quantum wells. In the temperature range of 77-297 K, thespin-polarized photocurrent shows an anisotropic spin transport under differentoriented in-plane electric fields. We ascribe this characteristic to twodominant mechanisms: the hot phonon effect and the Rashba spin-orbit effectwhich is influenced by the in-plane electric fields with differentorientations. The formulas are proposed to fit our experiments, suggesting aguide of potential applications and devices.
Record 7 of 10
Authors: Ren, KK; Wang, J; Liu, K; Huang, YB;Sun, Y; Azam, M; Jin, P; Wang, ZJ; Qu, SC; Wang, ZG RSC ADVANCES Volume: 9 Issue: 34 Pages: 19772-19779 Published: JUN24 2019 Language: English Documenttype: Article DOI: 10.1039/c9ra01689a Abstract: Controllable growth of perovskite nanowires is veryimportant for various applications in optical and electrical devices. Althoughsignificant progress has been achieved in the solution method, a deepunderstanding of the mechanics of growing perovskite nanowires is stilllacking. Herein, we developed an electrochemical method for growing theperovskite nanowires and studied the growth processes systematically. Theinitial nucleation and crystal growth could be controlled by simply varying theadditive solvents, thus leading to two stable size ratio distributions of theperovskite nanowires. Further, with compositional engineering, the bandgap ofthe perovskites could be tuned from 1.59 eV to 3.04 eV. All the as-grownperovskite nanowires displayed a unique structure with high crystallizationquality, contributing to a very high responsivity of 2.1 A W-1 and a largeon/off ratio of 5 x 10(3) for the photodetectors based on the CH3NH3PbBr3nanowires. All of these findings demonstrate that the optimized solution methodoffers a new approach to synthesize perovskite nanowires for applications inphotoelectric devices.
Record 8 of 10
Authors: Yang, S; Zhang, JY; Yang, YY; Huang, JY;Bai, YR; Zhang, Y; Lin, XC RESULTS IN PHYSICS Volume: 13 Published: JUN2019 Language: English Documenttype: Article DOI: 10.1016/j.rinp.2019.102201 Abstract: We present a technique for compensating laser beamup-shifting induced by the hot air with temperature gradient in a 2D-scaninglaser radar for monitoring the intruder in the railway system, in which thelaser beam is scanning at a height only a few centimeters above the railwaytracks so that any object with a size of 5 cm x 5 cm x 5 cm or larger can bedetected. It is found that when the laser beam is traveling in the hot air witha temperature gradient, the direction of the laser can be up-shifted. Theup-shifted laser beam may miss the obstacle lies on the railway track and failto detect and report the accidence and it may eventually result in a disaster.The compensation of the upward shifting is necessary to insure the normaloperation of the radar system and it can be done by using the difference inlinear thermal expansion between metals, which produce an additional elongationwhen the temperature changes. The temperature dependent elongation is used todrive a rotational stage, which rotates the laser in the opposite directionagainst the up-shifting. The rotation of the stage compensates the change ofangle of the laser beam induced by the temperature gradient of the air. Aprototype device is constructed to test the idea. Without thermal compensation,the laser thermal shift can reach up to 15 mm when temperature changes 14degrees C from 30 degrees C to 44 degrees C above the hot surface after thelaser beam travels 30 m and such a shift can be reduced to about 8 mm at thesame distance when the compensator system is used. The experimental data agreesvery well with the theoretical calculation.6
Record 9 of 10 Research on the Protrusions Near Silicon-Glass Interfaceduring Cavity Fabrication
Authors: Zhang, M; Yang, J; He, YR; Yang, F;Zhao, YM; Xue, F; Han, GW; Si, CW; Ning, J MICROMACHINES Volume: 10 Issue: 6 Published: JUN2019 Language: English Documenttype: Article DOI: 10.3390/mi10060420 Abstract: Taking advantage of good hermeticity, tiny parasiticcapacitance, batch mode fabrication, and compatibility with multiple bondingtechniques, the glass-silicon composite substrate manufactured by the glassreflow process has great potential to achieve 3D wafer-level packaging for highperformance. However, the difference in etching characteristics between siliconand glass inevitably leads to the formation of the undesired micro-protrusionsnear the silicon-glass interface when preparing a shallow cavity etched arounda few microns in the composite substrate. The micro-protrusions have acomparable height with the depth of the cavity, which increases the risks ofdamages to sensitive structures and may even trigger electrical breakdown, resultingin thorough device failure. In this paper, we studied the characteristics ofthe chemical composition and etching mechanisms at the interface carefully andproposed the corresponding optimized solutions that utilized plasmaaccumulation at the interface to accelerate etching and bridge the gap inetching rates between different chemical compositions. Finally, a smoothtransition of 131.1 nm was achieved at the interface, obtaining an idealetching cavity surface and experimentally demonstrating the feasibility of ourproposal. The micromachining solution is beneficial for improving the yield andstructural design flexibility of higher performance micro-electromechanicalsystems (MEMS) devices.
Record 10 of 10
Authors: Lu, XD; Li, J; Su, K; Ge, C; Li, ZC;Zhan, T; Wang, GH; Li, JM NANOMATERIALS Volume: 9 Issue: 6 Published: JUN2019 Language: English Documenttype: Article DOI: 10.3390/nano9060862 Abstract: A 365-nm UV LED was fabricated based on embeddednanoporous AlGaN distributed Bragg reflectors (DBR) by electrochemical etching.The porous DBR had a reflectance of 93.5% at the central wavelength of 365 nm;this is the highest value of porous AlGaN DBRs below 370 nm which has beenreported so far. An innovative two-step etching method with a SiO2 sidewallprotection layer (SPL) was proposed to protect the n-AlGaN layer and activeregion of UV LED from being etched by the electrolyte. The DBR-LED with SPLshowed 54.3% improvement of maximal external quantum efficiency (EQE) and 65.7%enhancement of optical power at 100 mA without any degeneration in electricalproperties, compared with the un-etched standard LED sample. This work has pavedthe way for the application of electrically-pumped UV LEDs and VCSELs based onnanoporous AlGaN DBRs.
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Record 1 of 13
Authors: Zhao, S; Yuan, GD; Wang, Q; Liu, WQ;Zhang, S; Liu, ZQ; Wang, JX; Li, JM APPLIED SURFACE SCIENCE Volume: 489 Pages: 776-785 Published: SEP30 2019 Language: English Documenttype: Article DOI: 10.1016/j.apsusc.2019.06.032 Abstract: Micro-/nano-structures enable crystalline silicon (c-Si)to be prominent in many fields. In this work, an elaborate study on texturingc-Si via copper-assisted chemical etching (Cu-ACE) is reported. Variouslarge-area craters arrays including gyro-like craters arrays, standard invertedpyramids arrays and deformed inverted pyramids arrays, together with mesoporoussurfaces and polished-like surfaces are synthesized on Si wafers with Cu-ACE.An electrokinetic "H2O2 consumption" model and an energy band modelare proposed to explain the synergetic effects between isotropic andanisotropic etching on preparing Si micro-/nano-structures during etching. Itis demonstrated that the etched morphology is determined by the temporal H2O2relative concentration at etch end-points, which is accurately controlled byetching conditions. A "curved sidewalls" model is put forward, forthe first time, to illustrate the nuances among etched craters arrays. Based onthis model, the local H2O2 relative concentration determines local curvaturesof sidewalls. Textured Si wafers with inverted pyramids arrays exhibitexcellent anti-reflection abilities and are promising for solar cells,photodiodes or other optoelectronic applications. Notably, our work provides afacile and controllable approach to produce various Si micro-/nanostructureswhich are of practical values in many domains.
Record 2 of 13
Authors: Zhang, ZY; Fan, WL; Wei, XC; Zhang, L;Yang, ZL; Wei, Z; Shen, T; Si, HN; Qi, JJ JOURNAL OF ALLOYS AND COMPOUNDS Volume: 802 Pages: 694-703 Published: SEP25 2019 Language: English Documenttype: Article DOI: 10.1016/j.jallcom.2019.06.161 Abstract: Although carbon based hole-conductor-free perovskitesolar cells have acquired interest in the scientific community in the past fewyears, some issues with regard to relatively low efficiency and toxicity needto be addressed before their commercialization. For the first time, theenvironmentally friendly ammonium acetate CH3COONH4 (NH4Ac) and Zn(CH3COO)(2) (ZnAc2)were adopted as additives for perovskite preparation. By introducing a verysmall amount (0.08%) of volatile NH4Ac through a simple one-step spin coatingmethod, high-quality perovskite layer with lower defect density, larger grainsize and pure perovskite composition without alien atom was obtained, resultingin a power conversion efficiency (PCE) of 13.9%, which is similar to 25%enhancement compared to that of the device without additive. Moreover,stability was also investigated, 6% degradation appeared in PCE of NH4Ac sampleafter being stored for 1900h in dark. The promoted interface contact ofcarbon/perovskite results in higher efficiency and longer stability of NH4Acadded perovskite solar cell (PSC). On the other hand, addition of non-volatileZnAc2 only lead to a slight enhancement of the efficiency. The factorsaffecting the properties will be discussed in detail. (C) 2019 Elsevier B.V.All rights reserved.
Record 3 of 13 The mechanism of the electrochemical oxidation in theconstant current mode of the porous silicon
Authors: He, L; Zhang, XN; Wang, YG; Wang, WJ MATERIALS RESEARCH EXPRESS Volume: 6 Issue: 9 Published: SEP2019 Language: English Documenttype: Article Abstract: In order to clarify the mechanism of the electrochemicaloxidation (ECO) in the constant current mode of porous silicon (PS), the ECOprocess of PS in different concentration of electrolyte was studied in detail.According to the experiment facts, a hypothesis based on the mechanism of'electrical break' was first proposed to explain the oxidation interruptionthat tends to occur in the lower concentration of the electrolyte. Theexperiment results show that the bottom of the porous layer is preferentialoxidized in the ECO process since the oxidation process was governed by theholes injected from the substrate and supplied to the silicon-electrolyteinterface. The appearance of the oxidation interruption during the ECO processis due to the electrical isolation between the Si substrate and electrolyte bythe formation of a continuous oxide film at the bottom of the porous layer. Theresults obtained in this work indicated that it is easy to control thethickness of the oxide film by adjusting the concentration of electrolyte,which made the ECO method appears to be more attractive when incompleteoxidation is required. This present work is also contributes to the fundamentalunderstanding of the ECO mechanism in the constant current mode of the PSmaterial.
Record 4 of 13
Authors: Kang, JJ; Choi, HJ; Ren, F; Ao, JP; Li,HJ; Li, Y; Du, WC; Zhou, K; Tan, H; Huh, D; Li, PP; Liang, M; Gao, SX; Tang, C;Yi, XY; Lee, H; Liu, ZQ JAPANESE JOURNAL OF APPLIED PHYSICS Volume: 58 Issue: 8 Published: AUG1 2019 Language: English Documenttype: Article Abstract: In this research, an InGaN/GaN nanotube-based photoanodehas been fabricated by nano-imprint lithography and a secondary sputteringprocess. The involvement of a Au nano-ring mask allowed dry etching with a highaspect ratio on the InGaN/GaN substrate. After device fabrication, the measuredoptical spectrum showed this innovative structure provided low reflectance andhigh absorbance at the wavelength around the ultraviolet range. Thephotoelectrochemical properties indicated optimized tube height couldefficiently enhance the water splitting efficiency by 15 times at 1.23 V versusRHE by increasing the surface reactive area and tuning the optical spectrumproperties. The IPCE result also demonstrated a corresponding enhancement. (C)2019 The Japan Society of Applied Physics
Record 5 of 13 Wavelength-Tunable Chaotic Signal Generation With On-ChipO/E Conversion
Authors: Chen, GC; Zhao, W; Lu, D; Guo, L; Wang,H; Zhou, DB; Huang, YG; Liang, S; Zhao, LJ IEEE PHOTONICS TECHNOLOGY LETTERS Volume: 31 Issue: 14 Pages: 1179-1182 Published: JUL15 2019 Language: English Documenttype: Article Abstract: A wavelength-tunable chaotic optical signal generationand on-chip O/E conversion scheme based on an integrated laser-photodiode chipsubject to filtered optical feedback is proposed and experimentallydemonstrated. The integrated chip consists of a Fabry-Perot (FP) gain sectionand a photodiode, which was fabricated on an n-InP substrate with the sameactive material. By applying a filtered feedback signal to the FP gain section,wavelength-tunable chaotic carrier ranging from 1576 to 1587 nm was achieved.On-chip microwave chaotic signal generation with a standard bandwidth over 5.5GHz was obtained using the integrated photonic chip.
Record 6 of 13 FCC-compliant millimeter-wave ultra-wideband pulsegenerator based on optoelectronic oscillation
Authors: Zhu, S; Fan, XJ; Li, M; Zhu, NH; Li, W OPTICS LETTERS Volume: 44 Issue: 14 Pages: 3530-3533 Published: JUL15 2019 Language: English Documenttype: Article DOI: 10.1364/OL.44.003530 Abstract: We report a photonic scheme to generate a millimeter-waveultra-wideband (MMW-UWB) pulse based on optoelectronic oscillation (OEO).Normally, a millimeter-wave signal source is essential for the generation of aMMW-UWB pulse. The key novelty of our work is that no millimeter wave signalsource is required. The MMW-UWB pulses are directly generated by truncating anOEO signal into pulses. The principle behind the proposed scheme is analyzed indetail. A proof-of-concept experiment shows that the generated MMW-UWB pulsesfit the Federal Communications Commission (FCC) spectral mask very well. (C)2019 Optical Society of America
Record 7 of 13 Processing Halide Perovskite Materials with SemiconductorTechnology
Authors: Cheng, CT; Zhu, C; Huang, BJ; Zhang, H;Zhang, HJ; Chen, R; Pei, WH; Chen, Q; Chen, HD ADVANCED MATERIALS TECHNOLOGIES Volume: 4 Issue: 7 Published: JUL2019 Language: English Documenttype: Article Abstract: Semiconductor technologies make major contributions toscientific and technological improvements, enabling high-performance andlow-cost devices, chips, and systems. Photolithography technologies are at theheart of semiconductor technologies and are indispensable in fabricatingmicrostructures and nanostructures. It is obvious that a new emerging materialcan play a greater role in economic development if it can be processed withphotolithography technologies. Halide perovskites have received an enormousamount of attention, as they are useful in photonic and optoelectronicapplications due to their strong optical absorption, tunable direct bandgap,and long electron-hole diffusion length. However, photolithography technologiescannot be utilized to fabricate semiconductor devices based on halideperovskite materials because water, a solvent for all halide perovskitematerials, is used in the fabrication process. Here, the process compatibilitybetween halide perovskite materials and semiconductor technology is realizedwith the help of parylene, a kind of polymer. A photodetector based on MAPbI(3)and a memristor based on CsPbBr3 fabricated with photolithography technologiesare both demonstrated successfully for the first time. This study not onlypaves the way toward the fabrication of halide perovskite devices withsemiconductor technologies but also provides a powerful tool for the in-depthstudy of halide perovskite materials.
Record 8 of 13 Epitaxial Liftoff of Wafer-Scale VO2 Nanomembranes forFlexible, Ultrasensitive Tactile Sensors
Authors: Li, XX; Yin, ZG; Zhang, XW; Wang, Y;Wang, DG; Gao, ML; Meng, JH; Wu, JL; You, JB ADVANCED MATERIALS TECHNOLOGIES Volume: 4 Issue: 7 Published: JUL2019 Language: English Documenttype: Article Abstract: Highly sensitive tactile sensors with long-term stabilityand low power consumption are one of the key components for flexibleelectronics. Here, for the first time, the fabrication of VO2 nanomembranetactile sensors by epitaxial liftoff from ZnO sacrificial layer is reported.The wafer-scale nanomembranes inherit the structural and electrical propertiesof the as-grown films, and the wet transfer generates negligible influence onthe quality of VO2. Most importantly, giant electrical responses to externalstrains are found due to the release of substrate clamping, and a high gaugefactor up to approximate to 1100 is derived. Furthermore, the electricalproperties show no deterioration after repeatedly bending the nanomembranes for10 000 times at a radius of 1 cm. The VO2 nanomembrane sensors are utilized tomonitor the radial artery pulse, and totally reproducible waveforms withultrahigh sensitivity to the tactile stimuli are observed. Moreover, the powerdissipation of the VO2 tactile sensors can be lowered down to the picowattlevel, allowing for the future construction of self-powered sensing systemstogether with nanogenerators. This study provides a substantial step towardlarge-scale preparation of oxide nanomembranes and therefore paves a promisingway for flexible oxide electronics.
Record 9 of 13 CL-TWE Mach-Zehnder electro-optic modulator based onInP-MQW optical waveguides
Authors: Qian, G; Niu, B; Zhao, W; Kan, Q; Gu,XW; Zhou, FJ; Kong, YC; Chen, TS CHINESE OPTICS LETTERS Volume: 17 Issue: 6 Published: JUN10 2019 Language: English Documenttype: Article Abstract: In this Letter, we reported the preliminary results of anintegrating periodically capacitive-loaded traveling wave electrode (CL-TWE)Mach-Zehnder modulator (MZM) based on InP-based multiple quantum well (MQW)optical waveguides. The device configuration mainly includes an opticalMach-Zehnder interferometer, a direct current electrode, two phase electrodes,and a CL-TWE consisting of a U electrode and an I electrode. The modulator wasfabricated on a 3 in. InP epitaxial wafer by standard photolithography,inductively coupled plasma dry etching, wet etching, electroplating, etc.Measurement results show that the MZM exhibits a 3 dB electro-optic bandwidthof about 31 GHz, a V-pi of 3 V, and an extinction ratio of about 20 dB.
Record 10 of 13
Authors: Xie, SW; Yang, CG; Huang, SS; Yuan, Y;Zhang, Y; Shang, JM; Cai, CY; Zhang, Y; Xu, YQ; Ni, HQ; Niu, ZC SUPERLATTICES AND MICROSTRUCTURES Volume: 130 Pages: 339-345 Published: JUN2019 Language: English Documenttype: Article DOI: 10.1016/j.spmi.2019.05.002 Abstract: The 2.1-mu m-wavelength InGaSb/AlGaAsSb/GaSb doublequantum well lasers, exhibiting a high performance with the peak output powerof 1.62 W and the maximum conversion efficiency of 27.5%, had been grown bymolecular-beam-epitaxy (MBE). Digitally grown AlxGa1-xAsSb barriers and gradinglayers were employed in the devices to increase the valence-band offset and toimprove the simplicity and controllability of MBE growth. The quaternarydigital alloys were grown with short-period superlattices (SPS) of AlSb, AlAsand GaSb and varieties of growth conditions such as growth temperature,interface control and growth rate were considered to get the high-qualitycrystal films. The digitally grown film was parametrically characterized byatomic force microscopy, high resolution X-ray and transmission electronmicroscope, showing a smooth surface, clear satellite peaks and clear growthcross sections, respectively. Besides the good power performance of thedevices, a low threshold current density of 60 A/cm(2) was also achieved andthe calculated differential resistance was 0.17 Omega.
Record 11 of 13 Improved Epitaxy of AlN Film for Deep-UltravioletLight-Emitting Diodes Enabled by Graphene
Authors: Chen, ZL; Liu, ZQ; Wei, TB; Yang, SY;Dou, ZP; Wang, YY; Ci, HN; Chang, HL; Qi, Y; Yan, JC; Wang, JX; Zhang, YF; Gao,P; Li, JM; Liu, ZF ADVANCED MATERIALS Volume: 31 Issue: 23 Published: JUN2019 Language: English Documenttype: Article Abstract: The growth of single-crystal III-nitride films with a lowstress and dislocation density is crucial for the semiconductor industry. Inparticular, AlN-derived deep-ultraviolet light-emitting diodes (DUV-LEDs) haveimportant applications in microelectronic technologies and environmentalsciences but are still limited by large lattice and thermal mismatches betweenthe epilayer and substrate. Here, the quasi-van der Waals epitaxial (QvdWE)growth of high-quality AlN films on graphene/sapphire substrates is reportedand their application in high-performance DUV-LEDs is demonstrated. Guided bydensity functional theory calculations, it is found that pyrrolic nitrogen ingraphene introduced by a plasma treatment greatly facilitates the AlNnucleation and enables fast growth of a mirror-smooth single-crystal film in avery short time of approximate to 0.5 h (approximate to 50% decrease comparedwith the conventional process), thus leading to a largely reduced cost.Additionally, graphene effectively releases the biaxial stress (0.11 GPa) andreduces the dislocation density in the epilayer. The as-fabricated DUV-LEDshows a low turn-on voltage, good reliability, and high output power. Thisstudy may provide a revolutionary technology for the epitaxial growth of AlNfilms and provide opportunities for scalable applications of graphene films.
Record 12 of 13 Analysis and optimization of 1.5-mu m InGaAsP/InP MQWselectroabsorption modulator
Authors: Zhou, DB; Liang, S; Wang, HT; Zhao, W;Zhang, RK; Zhao, LJ; Wang, W OPTIK Volume: 182 Pages: 1088-1092 Published: APR2019 Language: English Documenttype: Article DOI: 10.1016/j.ijleo.2019.02.011 Abstract: The effects of doping profile and well thickness on thelight extinction properties of electroabsorption modulators (EAM) are studiedexperimentally. It is found that both light p type doping in the InP claddinglayer and a large well thickness help to get higher extinction ratios at agiven reverse bias voltage. A 3D EAM model has been built for optimizing theperformance of EAMs. The simulation results are in a good agreement with theexperimental results. With the optimized EAM designs, a modulator with an over 20dB extinction ratio at a low bias voltage is demonstrated.
Record 13 of 13
Authors: Wei, QG; Zhu, S; Wang, YJ; Gao, XR; Guo,H; Wu, X IEEE ACCESS Volume: 7 Pages: 85452-85461 Published: 2019 Language: English Documenttype: Article DOI: 10.1109/ACCESS.2019.2925078 Abstract: Various improved canonical correlation analysis (CCA)methods were developed for enhancing the performance of steady-state visualevoked potential (SSVEP)-based brain-computer interfaces (BCIs). Among them,the method combining CCA spatial filters from sine-cosine references andindividual templates yielded the highest performance. However, the CCA aims tooptimize the correlation between two sets of variables rather than thesignal-to-noise ratio (SNR) of the SSVEP signals, upon which the performance ofan SSVEP-based BCI depends mainly. In this paper, a novel algorithm, namely,maximum signal fraction analysis (MSFA), is proposed for creating spatialfilters based on individual training data. The spatial filter for a specificstimulus target is estimated by directly maximizing the averaged SNR of theobserved signals across multiple trials. An individual template is calculatedfor each target by averaging training signals of multiple trials. Targetrecognition is based on template matching between filtered template signals anda single-trial testing signal. Classification performance of the MSFA-basedmethod was evaluated on a benchmark dataset and compared with that of theCCA-based methods. The results suggest that the proposed MSFA methodsignificantly outperforms the CCA-based methods in terms of classificationaccuracy, and thus, it has great potential to be applied in the real-lifeSSVEP-based BCI systems.
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