图形衬底量子线生长制备与荧光特性研究

报道了在V型槽图形衬底上利用分子束外延技术外延生长的GaAs/AlGaAs量子线.外延截面在扫描电子显微镜下可以看到在V型槽底部形成了弯月型量子线结构,量子线尺寸约为底边60 nm高14 nm的近三角形.低温87 K下光致发光谱测试在793.7和799.5 nm处出现峰值,验证了量子线的存在.理论近似计算结果显示,相比等宽度量子阱有8 meV的蓝移正是由于横向量子限制引起的. 关键词： V型槽图形衬底 量子线 GaAs     

基于InAs单量子点的单光子干涉

利用分子束外延生长 InAs 单量子点样品,测量了温度为 5 K 时单量子点的荧光(PL)光谱.采用时间关联光子强度测量(HBT)验证了 PL 光谱具有单光子发射特性.单光子通过马赫曾德尔 (MZ) 干涉仪,验证了单光子自身具有干涉特性.测量了当 MZ 干涉仪两臂偏振方向的夹角改变时对应的单光子干涉及条纹可见度的变化. 关键词： 量子点单光子源 反群聚效应 马赫曾德尔干涉     

基于二维材料异质结的光探测器研究进展

二维材料异质结因其特有的层状结构和优异的光响应性质,被认为具有应用于新一代光探测器件的潜力.二维材料家族具有丰富的种类,因其能带带隙范围分布广,光电响应可覆盖从紫外到红外的波谱范围.另外二维材料层间通过范德瓦尔斯力相结合,因此理论上可以利用不同二维材料层间的范德瓦尔斯力相互作用制备出多种性能优异的二维材料异质结.近年来有多种二维材料异质结通过机械堆叠法及CVD生长法被制备出来,且二维材料异质结光探测器在可见光至远红外波段表现出优异的性质.在这样的研究背景之下,本文从二维材料异质结的制备、器件制备与器件性能等几个方面综述了近年来二维材料异质结光探测器的研究进展.     

2-μm single longitudinal mode GaSb-based laterally coupled distributed feedback laser with regrowth-free shallow-etched gratings by interference lithography

We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm~2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.     

Proper In deposition amount for on-demand epitaxy of InAs/GaAs single quantum dots

The test-QD in-situ annealing method could surmount the critical nucleation condition of InAs/GaAs single quantum dots(SQDs) to raise the growth repeatability.Here,through many growth tests on rotating substrates,we develop a proper In deposition amount(θ) for SQD growth,according to the measured critical θ for test QD nucleation(θ_c).The proper ratio θ/θ_c,with a large tolerance of the variation of the real substrate temperature(T_(sub)),is 0.964-0.971 at the edge and 0.989 but 0.996 in the center of a 1/4-piece semi-insulating wafer,and around 0.9709 but 0.9714 in the center of a 1/4-piece N~+ wafer as shown in the evolution of QD size and density as θ/θ_c varies.Bright SQDs with spectral lines at 905 nm-935 nm nucleate at the edge and correlate with individual 7 nm-8 nm-height QDs in atomic force microscopy,among dense 1 nm-5 nm-height small QDs with a strong spectral profile around 860 nm-880 nm.The higher T_(sub) in the center forms diluter,taller and uniform QDs,and very dilute SQDs for a proper θ/θ_c:only one 7-nm-height SQD in25 μm~2.On a 2-inch(1 inch = 2.54 cm) semi-insulating wafer,by using θ/θ_c = 0.961,SQDs nucleate in a circle in 22%of the whole area.More SQDs will form in the broad high-T_(sub) region in the center by using a proper θ/θ_c.     

超薄有源层谐振腔增强型调制器

提出利用超薄有源层制备高性能谐振腔增强型(RCE)半导体电吸收调制器件的可能性,并与波导型器件进行性能对比;对透射和反射两种类型器件优化分析了器件结构,进行了性能比较,结果表明:在插入损耗相当的情况下,反射式器件具有更高的调制对比度.     

Temperature dependence on the electrical and physical performance of InAs/AlSb heterojunction and high electron mobility transistors

In this report, the effect of temperature on the In As/Al Sb heterojunction and high-electron-mobility transistors(HEMTs) with a gate length of 2 μm are discussed comprehensively. The results indicate that device performance is greatly improved at cryogenic temperatures. It is also observed that the device performance at 90 K is significantly improved with 27% lower gate leakage current, 12% higher maximum drain current, and 22.5% higher peak transconductance compared to 300 K. The temperature dependence of mobility and the two-dimensional electron gas concentration in the In As/Al Sb heterojunction for the temperature range 90 K-300 K is also investigated. The electron mobility at 90 K(42560 cm2/V·s)is 2.5 times higher than its value at 300 K(16911 cm~2/V·s) because of the weaker lattice vibration and the impurity ionization at cryogenic temperatures, which corresponds to a reduced scattering rate and higher mobility. We also noted that the two-dimensional electron gas concentration decreases slightly from 1.99 × 10~(12) cm~(-2) at 300 K to 1.7 × 10~(12) cm~(-2) at 90 K with a decrease in temperature due to the lower ionization at cryogenic temperature and the nearly constant ?Ec.     

Metamorphic InGaAs Quantum Well Laser Diodes at 1.5μm on GaAs Grown by Molecular Beam Epitaxy

We report a 1.5-μm InGaAs/GaAs quantum well laser diode grown by molecular beam epitaxy on InGaAs metamorphic buffers. At 150K, for a 1500×10μm^2 ridge waveguide laser, the lazing wavelength is centred at 1.508 μm and the threshold current density is 667 A/cm^2 under pulsed operation. The pulsed lasers can operate up to 286 K.     

A method to obtain ground state electroluminescence from 1.3μm emitting InAs/GaAs quantum dots grown by molecular beam epitaxy

1.3μm emitting InAs/GaAs quantum dots(QDs) have been grown by molecular beam epitaxy and QD light emitting diodes(LEDs) have been fabricated.In the electroluminescence spectra of QD LEDs,two clear peaks corresponding to the ground state emission and the excited state emission are observed.It was found that the ground state emission could be achieved by increasing the number of QDs contained in the active region because of the state filling effect.This work demonstrates a way to control and tune the emitting wavelength of QD LEDs and lasers.     

1.55 μm低温生长GaAs谐振腔增强型探测器

利用低温（200℃）生长的GaAs材料作为吸收层制备了GaAs基1.55 μm谐振腔增强型（RCE） 光电探测器,对其光电特性进行了分析、研究.无光照0偏压下探测器暗电流为8.0×10－12A;光电流谱峰值波长1563 nm;响应谱线半宽4 nm, 具有良好的波长选择性.