高灵敏度GaAs/AlGaAs多量子阱狭带红外探测器

在半导体超晶格研究基础上,发展了以量子阱内电子由束缚基态至势垒顶附近连续态跃迁为机理的长波长红外探测器,这也是近几年来发展的一种新型红外探测器。它具有响应速度快、量子效率高、可变波长、热稳定性和均匀性好的优点,在军事和民用上占有重要地位,已成为国际上极为重视的高技术研究的前沿课题。1985年West和Eglash首先观察到GaAs量子阱中的光跃迁现象。在1987年levine等人制造出第一个GaAs/AlGaAs多量子阱红外探测器,近年又制造出性能更好的探测器:工作温度77K,峰值波长为8μm,峰值探测率D_(λρ)~*=4.0×10~(10)cm、(Hz)~(1/2)/W。     

InGaAsSb多量子阱材料的光致发光特性研究

研究了InGaAsSb多量子阱材料光致发光特性。通过实验数据分析和理论计算,发现对于分子束外延(MBE)法生长的InGaAsSb多量子阱材料,生长时的衬底温度决定着材料的质量,合适的衬底温度可以明显的增加其发射的光致发光强度;组分相同时,在一定范围内,随着阱厚的增加,其发射的光致发光波长也随着增加,但是随着阱厚增大,波长增加趋于平缓。     

红外探测器光谱响应率定标方法

采用新的方法对波长范围1-3μm的红外探测器绝对光谱响应率进行定标.红外探测器的光谱响应率定标是在两套定标系统上利用两种参考探测器实现的.首先在红外光谱比较系统上利用一个平响应的腔式热电堆探测器作为参考探测器,测量待测红外探测器相对于标准探测器的连续光谱响应率;然后在可见一近红外定标系统上,利用低温辐射计和激光器在几个单立波长上进行绝对光谱响应率测量.这样,通过计算就能得出待测红外探测器在每个波长上的绝对光谱响应率.采用上述方法对TS-76探测器进行光谱响应率定标,联合不确定度小于0.95%.     

Al0.15Ga0.85As／GaAs与In0.15Ga0.85As／GaAs甚长波QWIPs响应率的仿真对比

对In0.15Ga0.85As／GaAs和Al0.15Ga0.85As／GaAs两种甚长波段量子阱红外探测器（QwIP）响应率进行计算。采用物理模型与等效电路模型，结合Crosslight和Spice等软件详细表征了这两种QWIPs的吸收系数、暗电流、响应率、量子效率等物理特性。结果表明随外加偏压的升高QWIP的响应率增加，T=40K时，In0.15Ga0.85As／GaAs QwIP的响应率明显比Al0.15Ga0.85As／GaAs QWIP高出2倍以上，通过对量子效率的对比，使仿真结果得到验证。     

单结GaAs量子阱太阳能电池

介绍了采用金属有机化学气相沉积方法制备的单结GaAs量子阱太阳能电池.X射线双晶衍射表明电池中的材料缺陷较少,具有良好结晶质量与周期性.光谱响应实验表明量子阱结构的引入可以扩展吸收光谱.与无量子阱结构的电池相比,量子阱电池增加了输出电流,但同时也带来了开路电压的下降.量子阱电池在长波范围内短路电流明显增加,使得量子阱电池可以代替三结电池中的中间电池,优化电池结构设计,提高三结电池的转换效率.     

基于ZnO半导体纳米线膜的声表面波型紫外探测器

针对传统半导体光电探测器件结构的宽带隙半导体紫外探测器可测信号弱的问题,提出了一种基于ZnO纳米线膜的声表面波型紫外探测器.该探测器利用ZnO纳米线膜的强紫外光电响应特性和声表面波器件的灵敏的声电相互作用机制,将采用高纯锌粉的热蒸发氧化工艺制备的纤锌矿型ZnO纳米线制作在已有声表面波小波传感器上.利用光致发光谱研究发现,由于低维激子限域效应和表面效应,所制作ZnO纳米线敏感膜中的紫外光电效应优于外延ZnO半导体薄膜;同时,基于ZnO纳米线膜的声表面波式紫外探测器在紫外光辐照下该探测器的中心频率减小,损耗增大.实验研究表明该器件能够实现长波紫外光的高灵敏度探测.     

荧光量子效率绝对法测量系统校准及不确定度评定

荧光量子效率是发射与吸收的光子数之比,是表征荧光材料发光性能的关键参数。然而,用于绝对法测量荧光量子效率的光路和探测器未经校准溯源或是校准方法不当,会造成测量光谱的不准确,进一步影响荧光量子效率计算结果的不准确。采用汞氩灯对单色仪进行校准,保证了激发波长和发射波长的准确性,利用标准辐射源对光路、发射单元单色仪和探测器进行光谱相对强度校准,保证了激发波段和发射波段光谱相对强度的准确性;最后从测量模型出发,对测量不确定度进行了分析,得到在300~360nm的激发光波段和370~900nm的发射光波段内相对合成标准不确定度为3.58%,相对扩展不确定度为7.16%,k=2。通过对单色仪波长校准以及对光谱相对强度进行校准,为荧光量子效率的准确测量提供了参考。     

基于物理机理和器件模型下对红外光子探测器的研究

红外探测范畴内的根本模型,涵盖了制备好的器件模型。红外探测特有的设备,要依循本源的物理机理,妥善予以制备。红外光子特有的探测器,在设定好的温度以内,要比对不同态势下的探测率。制备好的探测器,涵盖着设定出来的不同机理。要经由比对,明晰探测器特有的探测率、特有的工作温度、关联的响应波长。     

隧穿型量子效应薄膜材料制备技术

探讨了隧穿型量子效应薄膜材料制备技术,并应用分子束外延方法制备了典型结构外延材料GaAs基共振隧穿二极管,经过器件验证,得到了较好的结果.重点讨论了关键制备技术,包括束流精细控制和间歇式生长方式,主要是为了生长出更接近完美的晶体结构和晶体表面,并分析了测试结果和器件验证结果,最终得出整套隧穿型量子效应薄膜材料制备技术.     

硅基低维红外探测薄膜材料的研究概况

Si基探测器与硅读出电路的单片集成不仅使光电芯片在性能上得到重要改善,还可极大地降低成本.在对量子阱、量子点原理描述的基础上,综述了它们应用于薄膜红外探测材料的研究进展,提出了近期工作的重点.     

Preparation of thin GaAs suspended membranes for gas micro-sensors using plasma etching

The GaAs/AlGaAs heterostructure layer system grown by MBE on GaAs substrate was designed to be used for micro-mechanical structure fabrication. In the first step, double-side aligned photolithography is carried out to define the etching masks on both sides of the substrate. After this, highly selective reactive ion etching (SRIE) of GaAs from the front side is used to determine the lateral dimensions of the membrane structure. The vertical dimension is defined by deep backside SRIE through a 300 μm thick GaAs substrate to the AlGaAs etch stop layer, hence the structure thickness is precisely determined by the thickness of MBE-grown GaAs layer over this etch stop layer. The last step is selective etching of the AlGaAs etch stop layer. The thermal resistance value of the membrane structure as high as 21 K/mW is achieved.     

GaAs VCSEL／MISS混合集成光子开关

报道了ＭＢＥ生长的ＧａＡｓ材料ＶＣＳＥＬ与ＭＩＳＳ混合集成构成的光子开关。将ＭＢＥ生长的超薄ＡｌＡｓ层氧化为ＡｘＯｙ层用作ＭＩＳＳ器件的超薄半绝缘层，从而解决了该半绝缘层厚度的精密控制以及与ＶＣＳＥ工艺相容的问题。该集成器件除光子开关功能外，还能实现光放大功能，并可用于自由空间光互连。     

Epitaxial growth of high quality AlGaAs/GaAs structures on atomically flat GaAs surfaces in deep dielectric windows cleaned using atomic hydrogen

An improved method to grow AlGaAs/GaAs structures on GaAs inside deep dielectric windows (DDWs) is reported. Samples which have undergone patterning and etching to form the DDWs were subjected to atomic hydrogen irradiation generated by a hydrogen cracker cell in a molecular beam epitaxy (MBE) system at a substrate temperature of approximately 450 °C and hydrogen background pressure of 10⁻⁶ torr. AlGaAs/GaAs quantum well structures of different well widths grown on GaAs inside the DDWs pre-cleaned using atomic hydrogen showed two to five times improvement in photoluminescence (PL) linewidth compared to samples with area inside the DDWs subjected to thermal oxide desorption at 580 °C. The GaAs surface inside the DDWs cleaned using atomic hydrogen is atomically flat surface with surface roughness of 0.252 nm. This value is five times lower compared to that in the sample subjected to thermal oxide desorption. The use of atomic hydrogen is shown to be effective for cleaning the GaAs surface inside the DDWs, making it possible for MBE re-growth of high quality AlGaAs/GaAs structures for optoelectronic integration.     

Evaluation of reactive ion etching processes for fabrication of integrated GaAs/AlGaAs optoelectronic devices

Reactive ion etching (RIE) was used for the fabrication of GaAs/AlGaAs optoelectronic devices (laser diodes and photodetectors) for optical interconnect applications. Smooth, vertical sidewalls with a smooth surface at the field were obtained after optimizing RIE conditions in BCl₃-formed plasma. Accurate in-situ monitoring of the etching process was realized by laser interferometry end-point detection. This led to good process control and reproducibility of the demanding fabrication of the optoelectronic devices. The RIE etching process did not affect the electrical properties of the device by increasing the surface recombination currents. Lasers with etched mirrors exhibited a threshold current density of 970 A cm⁻², which is one of the best values ever reported. The feasibility of a simple technology for the fabrication of optoelectronic circuits, based on a BCl₃ RIE process for laser mirror etching, has been demonstrated.     

Optimized structure of AlGaAs/GaAs double junction solar cells

In this paper, the sub-layers of AlGaAs/GaAs double junction (DJ) solar cell have been redesigned in order to achieve an optimum cell structure. It has been deduced with cooperation of detailed balance limit theory and structural behaviour of AlGaAs, that the Al_0.45Ga_0.55As is the best choice for top cell’s material in AlGaAs/GaAs DJ solar cell. Also, there is a trade-off between peak tunnelling current and transparency in tunnel junction which makes Al_0.07Ga_0.93As as the optimum tunnel junction of AlGaAs/GaAs cell. Finally, a smoothed reflectance senary-layer structure based on modified-DBR has been proposed to be used as anti-reflection coating of proposed structure. Also, the thickness and doping concentration level of different layers have been optimized.     

Multilayer contacts to AlGaAs/GaAs photodetector heterostructures

The processes occurring in a multilayer metallization during the fabrication of contacts to AlGaAs/GaAs quantum well heterostructures are analyzed using contact resistance measurements, microstructural analysis of the constituent metallic layers, and calculations of diffusion profiles. The influence of the diffusion processes and the structure of the layers on the contact resistance and reproducibility of contact characteristics is interpreted in terms of structural defects and chemical inhomogeneity of the layers.     

准连续5kW叠层激光二极管列阵

报导了5kW GaAs/AlGaAs叠层激光二极管列阵的制作过程和测试结果。通过金属有机物化学气相沉积方法实现分别限制单量子阱结构。1cm激光条的填充密度是705。采用80个激光条叠层封装，激光条间距是0.5mm，功率密度达1.25kW/cm^2，峰值波长是809.0nm，谱线宽度是4.8nm。     

InGaAsP/InP long wavelength quantum well infrared photodetectors

High quality InGaAsP/InP MQWs structures, grown by solid source molecular beam epitaxy, with different doping concentrations in the wells were investigated. High doping concentrations benefits absorption but is not good for dark current. The photocurrent spectra and peak values are sensitive to applied voltage. The total photocurrent comes from the electrons excited to two excited states. The decrease of the photocurrent peak value at high voltage can be explained by the reduction of photogenerated electrons. The detectivity of the InGaAsP/InP QWIP measured at a bias of − 2.5 V at 20 K is greater than , which is comparable to the GaAs/AlGaAs QWIPs.     

The effects of ionizing radiation on GaAs/AlGaAs and InGaAs/AlInAs heterojunction bipolar transistors

GaAs/AlGaAs and InGaAs/AlInAs Heterojunction Bipolar Transistors (HBTs) have been exposed to ⁶⁰Co γ-ray doses up to 100 MRad. The d.c. current gain of GaAs/AlGaAs devices showed small increases for doses up to 75 MRad, due to a faster decrease in base current relative to collector current. After 100 MRad, none of the original devices were operational because of failure of the base-collector contact metallization (TiPtAu). Devices with either Be- or C-doped base layers showed the same response to the γ-ray doses. The InGaAs/AlInAs HBTs showed a small decrease (<10%) in current gain after a total dose of 88 MRad and appear to be somewhat more resistant to damage from accumulated doses of radiation than comparable GaAs devices. GaAs/AlGaAs devices exposed to transient (120 nsec) pulses of high energy electrons show rapid recovery of both collector and base currents, with no long transient responses observed. Numerical simulations of the recovery of both GaAs- and InP-based HBTs after transient doses of ionizing radiation suggest that both are relatively immune to damage up to dose rates of 10¹¹ Rad s⁻¹ with faster recovery of the GaAs devices because of the shorter recombination times in this material.