Al_xGa_(1-x)As_ySb_(1-y)/GaSb的LPE生长与性质研究

在GaSb衬底上用LPE法生长了晶格匹配的AlGaAsSb外延层。用室温光致发光和X射线双晶衍射分别测量了材料的禁带宽度和晶格常数,并与用内插法计算的结果进行了比较。用C-V和van der Pauw法测量了样品的电学参数。用激光喇曼散射和低温光致发光研究了材料的光学性质,观察到了类GaSb的LO模和类AlSb的LO模以及LO声子与等离子激元的耦合模L_-;对x=0.2,y=0.025的样品,由低温到室温的变温光致发光测量确定的禁带宽度的温度系数为-3.2×10~(-4)eV/K。此外对于晶格失配,P型的原因以及PL谱峰的展宽等问题进行了讨论。     

组份变化的InGaAsSb/AlGaAsSb多量子阱结构对其X射线衍射及发光性质的影响

通过二元系和三元系结构参数计算四元系量子阱结构的晶格常数、禁带宽度等,设计了InGaAsSb/AlGaAsSb结构的MBE生长参数及工艺,利用X射线双晶衍射和PL谱研究了InGaAsSb/AlGaAsSb多量子阱结构特性和光学特性。X射线双晶衍射谱中出现了8条卫星峰,表明制备的InGaAsSb/AlGaAsSb多量子阱结构具有良好的结晶质量。利用光致发光光谱方法对制备的样品的光学性质进行了表征,结果表明,不同组份的InGaAsSb/AlGaAsSb多量子阱的发光峰波长随组份的变化在1.6~2.28 μm范围内可调,样品PL谱的半峰宽最窄可达22 meV。     

Capping vertically aligned InGaAs/GaAs(Sb) quantum dots with a AlGaAsSb spacer layer in intermediate‐band solar cell devices

This study demonstrated the feasibility of fabricating a highly stacked vertically aligned InGaAs/GaAs(Sb) quantum dot (QD) structure with an AlGaAsSb spacer layer for improving the device performance of QD intermediate‐band solar cell (QD‐IBSC) devices. The power‐dependent photoluminescence measurements of the proposed structure revealed a blueshift in the QD ground‐state emissions when the excitation power was increased, indicating the formation of an intermediate band inside the QD structure. Capping the InGaAs QDs with a GaAsSb layer prevented the QDs from collapsing because there was less In–Ga intermixing between the QDs and GaAsSb layer. In addition to maintaining the QD structure, the carrier lifetime was extended by tuning the energy band alignment of the InGaAs/GaAsSb QD structure. Inserting the AlGaAsSb layer into the spacer layer increased the band gap, which in turn increased the open‐circuit voltage of the QD‐IBSC. The QD‐IBSC in this work shows an extension of external‐quantum efficiency by up to 1200 nm (compared with a GaAs reference cell) through the absorption by QDs and increased the open‐circuit voltage from 0.67 to 0.70 V by adopting the AlGaAsSb spacer layer. These results confirm that adopting a columnar InGaAs/GaAs(Sb) QD structure with a AlGaAsSb spacer layer can enhance the performance of QD‐IBSC devices. Copyright © 2016 John Wiley & Sons, Ltd.     

Some perspectives and peculiarities of the LPE growth of multicomponent Sb-based solid solutions from pentanary liquid phases

The use of pentanary liquid phases to growth Sb-based solid solutions could improve the quality of these materials and of devices made from them. We discuss here two ways in which these improvements can be achieved. The first one concerns the growth of AlGaAsSb and InGaAsSb from “neutral” solvents in the Sb-rich corner of their phase diagrams. This technology could permit to keep the advantages of growing from Sb solvents and of decreasing the growth temperature at the same time. Another case is related to the control of critical supercooling during LPE growth of AlGaAsSb. We have found experimentally that the addition of In to a Sb-rich Al-Ga-As-Sb liquid phase increases the critical supercooling. In this way the quality of the heterostructure interfaces could be improved.     

2μm InGaSb/AlGaAsSb应变量子阱激光器的MBE生长研究

摘要：对InGaSb/AlGaAsSb应变量子阱和GaSb接触层掺Te的MBE生长进行了研究。通过原子力显微镜(AFM)、X射线衍射(XRD)设备、光致发光谱(PL)测试,对应变量子阱的生长参数进行了优化。量子阱室温PL测试,发光波长为1.98 μm,半峰宽为115nm。通过Hall测试优化了GaSb外延掺Te的生长参数,最优的掺杂浓度为1.1271018 cm-3,电阻率为5.29510-3Ω?cm。     

采用AlSb缓冲层生长2.3μm InGaAsSb/AlGaAsSb多量子阱结构

针对常见的GaSb衬底的InGaAsSb/AlGaAsSb多量子阱结构进行了设计和外延生长。样品通过X-射线测试,有多级衍射卫星峰出现,表明量子阱结构的均匀性和界面质量较好,引入AlSb缓冲层可以降低衬底与外延层之间的界面自由能,使AlSb起到了一个滤板的作用,抑制了位错的扩散。光荧光谱测试表明,室温下量子阱结构中心发光波长在2.3μm附近。     

2μm InGaAsSb/AlGaAsSb双波导半导体激光器的结构设计

为了提高2μm InGaAsSb/AlGaAsSb半导体激光器的最大输出功率,减小远场垂直发散角并实现单模稳定输出,在非对称波导结构的基础上设计了具有双波导结构的2μm InGaAsSb/AlGaAsSb半导体激光器.同时,利用相关的物理模型及SimLastip程序语言构建了InGaAsSb/AlGaAsSb Macro文件,利用SimLastip软件对具有不同结构的2μm InGaAsSb/AlGaAsSb半导体激光器进行了数值模拟分析.研究结果表明,双波导结构可以将半导体激光器的有源区限制因子由0.019 2减小至0.011 3,器件的最大输出功率提高了1.7倍,远场垂直发散角由57°减小到48°,器件性能得到了改善.     

High-temperature(T = 80℃) operation of a 2μm InGaSb-AlGaAsSb quantum well laser

正An InGaSb/AIGaAsSb compressively strained quantum well laser emitting at 2μm has been fabricated. An output power of 82.2 mW was obtained in continuous wave(CW) mode at room temperature.The laser can operate at high temperature(T = 80℃),with a maximum output power of 63.7 mW in CW mode.     

2μm InGaAsSb/AlGaAsSb应变补偿量子阱结构的数值研究

为了降低2μm半导体激光器的阈值电流并提高器件的输出功率,设计了InGaAsSb/AlGaAsSb应变补偿量子阱结构,并利用SimLastip软件对器件进行了数值模拟.研究表明,在势垒中适当引入张应变可以改善量子阱的能带结构,提高对载流子的限制能力.当条宽为120 μm、腔长为1 000 μm时,采用应变补偿量子阱结构的激光器的阈值电流为91 mA,斜率效率为0.48 W/A.与压应变量子阱激光器相比,器件性能得到明显的改善.     

High power 2-μm room-temperature continuous-wave operation of GaSb-based strained quantum-well lasers

A high power GaSb-based laser diode with lasing wavelength at 2 μm was fabricated and optimized. With the optimized epitaxial laser structure, the internal loss and the threshold current density decreased and the internal quantum efficiency increased. For uncoated broad-area lasers, the threshold current density was as low as 144 A/cm2 (72 A/cm2 per quantum well), and the slope efficiency was 0.2 W/A. The internal loss was 11 cm-1 and the internal quantum efficiency was 27.1%. The maximum output power of 357 mW under continuous-wave operation at room temperature was achieved. The electrical and optical properties of the laser diode were improved.