碲镉汞探测器在高温目标下的光电倍增效应

针对不同波段的碲镉汞红外探测器在探测高温目标情况下的特性进行了研究。测量结果显示随着所探测目标温度的不断升高,器件光生电流亦随之上升,但并非平行变化,这就导致了探测器动态微分阻抗不断下降。器件微分电阻下降的主要原因是p?蛳n结由于背景辐照和反向偏压的增加,引起光生载流子的激增,碰撞电离导致的光电倍增效应引起的,这种效应使得器件光生电流并非是单纯叠加在器件反偏暗电流之上、只随辐射通量而变化的变量,同时也是偏压的函数,随着偏压的增大会对微分阻抗有一个降低作用。通过理论计算这种假设得到了证实,实验结果和理论计算吻合的比较好。     

γ辐射对碲镉汞光伏探测器的暂态损伤与永久损伤

利用60Co γ源对碲镉汞光伏探测器进行了辐射损伤研究,通过电流-电压测试方法对器件的辐射效应进行了表征.利用数值微分方法得到器件较大反向偏压下的暗电流与缺陷中心密度的关系更为明显.通过研究辐射停止后器件的暗电流随着时间延长的变化,认为碲镉汞光伏探测器的γ辐射损伤存在暂态损伤和永久损伤.将这一现象进行实际应用,可以延长工作于辐射环境中的红外探测器的使用寿命.     

背景辐射对甚长波碲镉汞光导器件性能的影响

通过对甚长波碲镉汞器件的信号、噪声、有效寿命等的测试分析,研究背景辐射对甚长波器件性能的影响.利用冷光阑和黑体照射改变器件接收的背景辐射,设计并搭建了变背景有效寿命测试装置.改变背景辐射,测试甚长波器件的电阻、信号、噪声、噪声频谱、有效寿命.测量结果表明,增加立体角为30°的冷光阑后,随着背景辐射的减小,器件的电阻、信号、噪声、探测率等都有不同程度的增加;噪声频谱测试证明,1 kHz频率处的噪声主要是产生-复合噪声;改变黑体温度的变背景的有效寿命测试结果证明,背景辐射对寿命的影响很大,背景辐射减小,光生载流子的有效寿命增加.分析甚长波器件表面和体内的S-R复合、俄歇复合、辐射复合等复合机制,利用非平衡载流子和器件有效寿命理论对器件的寿命和产生复合噪声随背景辐射的变化进行理论计算,计算结果与实验结果存在一定的差异,但在随背景辐射变化的趋势上一致,并对两者的差别进行了分析.     

空间辐射环境与光器件抗辐射加固技术进展

随着光器件在空间环境和辐射环境中的广泛应用,在国际上对光器件抗辐射性能的研究越来越多。为了提高光器件的抗辐射性能,满足空间应用的各种需要,文章介绍了空间辐射环境,空间辐射对光器件的影响和辐射损伤机理,主要是光纤、激光器、光探测器、光纤陀螺的辐射效应和损伤机理。同时,概述了航天用光器件的抗辐射加固技术及其最新进展。通过采用抗辐射加固技术,大大提高了空间应用的超辐射发光二极管（SLD）、超荧光光纤（SFS）光源、1310nm波长的InGaAsP／InP半导体激光器、电荷耦合器件（CCD）、互补性金属氧化物半导体（CMOS）器件的抗辐射性能和可靠性。     

基于泊松过程的半导体激光器空间辐射效应研究

针对始终处于加电状态工作模式的半导体激光器,通过分析单个粒子对器件的辐射过程,将空间辐射效应离散的描述为所有单粒子造成辐射效应的累积。考虑到粒子到达服从泊松过程的特点,建立了半导体激光器空间辐射效应性能退化模型。推导了器件可靠度函数以及平均故障前时间的表达式。对InGaAs多量子阱激光二极管在高轨空间辐射环境中的性能退化过程进行了仿真,得到了器件的光功率退化曲线。结果表明光功率退化量与辐射时间近似成正比例关系。由此提出了同时考虑辐射与退火效应条件下,器件的光功率退化速率,通过拟合得出该速率与空间辐射平均剂量率成正比。获得了半导体激光器的可靠度曲线,进而计算了器件的平均故障前时间。     

新型结构垂直腔面发射激光器的研制

为改善垂直腔面发射半导体激光器(VCSEL)的热特性.提高其光电性能,研制了新型辐射桥结构的VCSEL,即采用辐射桥状的电流注入通道取代以往传统结构VCSEL的环形电流注入通道.研究表明辐射桥结构可以降低VCSEL器件的体电阻和热阻,改善器件的模式特性.在同一外延片上,采用相同的工艺制备了辐射桥结构与传统结构两种VCSEL器件,并对两种器件的光电性能进行了对比测试.结果表明,辐射桥结构VCSEL比传统结构的VCSEL微分电阻降低25%,输出功率提高到1.6倍;辐射桥结构的VCSEL具有良好的温度特性与模式特性,80℃时仍能正常激射,60℃时最大输出功率可达17 mW,器件的热阻可达1.95℃/mW;器件单模工作,其总体性能远优于传统结构的VCSEL器件.     

可调谐传感器

本发明提供一种能以特定的频率和宽带模式探测来自目标的红外光的可调谐测辐射热计器件。该器件中有一个像元列阵,该像元列阵上的每个像元通过控制可以敏感特定波长的光。通过这种探测,人们便可以对目标进行光谱分析。另外,该器件中的每个像元可以通过一个连带的校准器调谐到探测红外辐射的一个不同频率或者切换成对红外辐射进行宽带探测。     

GaN基发光二极管寿命测试及失效分析

将来自相同外延片和相同制作工艺的30只GaN基绿色发光二极管管芯分成3组,分别加30、40和60 mA电流进行不同时间的老化试验.在老化之前和老化期间测量了器件的光输出功率和I-V特性.将测得的光输出功率数据对时间进行指数函数拟合,得到了每一组器件的退化率及寿命,并推出器件在正常使用条件下的寿命.实验数据分析表明在电流应力作用下,GaN基绿色发光二极管的正向电压随着老化时间的增加单调上升,同时光功率下降.在60 mA下老化的管芯的串联电阻退化严重.对失效器件进行了失效机理分析.     

背景辐射对HgCdTe中波叠层光导器件噪声的影响

研究了HgCdTe中波叠层光导器件在不同背景辐射条件下的性能变化,设计了增加冷光栏和使用不同温度的黑体对器件进行辐照的两种改变背景辐射的实验方案.结果表明,随着背景辐射的减小,器件的测量噪声亦减小.利用非平衡载流子和器件有效寿命理论对器件的产生复合噪声进行了计算,计算结果与实验结果在随背景辐射变化的趋势上相似.进一步的噪声频谱测量表明,1/f噪声是叠层器件噪声随背景辐射变化的主要原因;而叠层结构中存在的边缘接触不对称MIS结构增大了背景辐射变化对1/f噪声的影响.     

背景辐射对HgCdTe中波叠层光导器件噪声的影响

研究了HgCdTe中波叠层光导器件在不同背景辐射条件下的性能变化,设计了增加冷光栏和使用不同温度的黑体对器件进行辐照的两种改变背景辐射的实验方案.结果表明,随着背景辐射的减小,器件的测量噪声亦减小.利用非平衡载流子和器件有效寿命理论对器件的产生复合噪声进行了计算,计算结果与实验结果在随背景辐射变化的趋势上相似.进一步的噪声频谱测量表明,1/f噪声是叠层器件噪声随背景辐射变化的主要原因;而叠层结构中存在的边缘接触不对称MIS结构增大了背景辐射变化对1/f噪声的影响.     

Silicon photodiode as a photosensitive capacitance

In this paper the influence of light on the junction capacitance of a silicon photodiode is discussed. The analysis carried out deals with an open-circuited and reverse-biased photodiode. In this analysis the dependence of the photocurrent sensitivity and the differential conductance on an illumination and an applied voltage is included. The dependence of the open-circuit voltage on an illumination, with the d.c. performance of a silicon diode at low currents taken into consideration, is also derived. The presented analysis shows that the specific performance of a photodiode gives possibilities to use this element in detecting very low illuminations.     

Voltage controlled minority carrier collection—the exponentially retrograded photodiode

The large retarding field in an exponentially retrograded photodiode is shown to significantly reduce the base-generated photocurrent at low reverse-bias voltages. Increasing the reverse voltage on the diode reduces the length over which this retarding field is effective, thereby increasing the Photo-Transmission Coefficient of the diode. From avalanche breakdown considerations, the largest ratio of change in photocurrent caused by this effect is shown to be only a function of the resistivity and bulk-lifetime in the base of the diode. This voltage-controlled collection effect is observable only in diodes with high background resistivity (i.e. silicon > 25 Ω cm.). It is theoretically possible to obtain voltage-controlled collection ratios of better than 50:1 in, typically, a 10 V junction swing.

Experimental results compare well with theoretical models.     

Photodiode Circuit Macro-model for SPICE Simulation

An accurate photodiode circuit macro-model is proposed for SPICE simulation. The definition and implementation of the macro-model is based on carrier stationary continuity equation. In this macro-model, the photodiode is a device of three pins, one for light intensity input and the other two for photocurrent output, which represent the relationship between photocurrent and incident light. The validity of the proposed macro-model is demonstrated with its PSPICE simulation result compared with reported experimental data.     

A numerical analysis of a heterostructure InP/InGaAs photodiode

Electrical properties of a heterostructure InP/In0.53Ga0.47- As photodiode have been analyzed numerically. A device simulator, which can handle a heterostructure up to a high voltage operation, was developed for this work. The numerical simulator explains the experimental results obtained regarding photocurrent. The band-gap discontinuities, i.e., 0.22 eV for the conduction band and 0.37 eV for the valence band, were confirmed to be plausible. The photocurrent switching mechanism in the photodiode by bias voltage was clarified through carrier and potential distributions. It was revealed that the photo-excited holes accumulate at the heterointerface, and the switching voltage for photocurrent varies according to the incident optical power level. It is expected that this simulator will be a powerful tool for optimum heterostructure photodiode design.     

Optical and noise characteristics of amorphous Si/SiC superlatticereach-through avalanche photodiodes

In order to improve the performance of the a(amorphous)-Si:H/SiC:H superlattice avalanche photodiode (APD), a-Si:H/SiC:H superlattice reach-through APDs (SRAPDs) have been fabricated on ITO(indium tin oxide)/glass substrates by plasma-enhanced chemical vapor deposition (PECVD). For a typical electron-injection SRAPD, the ratio of room-temperature electron and hole impact ionization rates (α/β) is 10.2 at an electric field 3.33×10⁶ V/cm, the optical gain is 506 at an applied reverse-bias V_R=18 V and an incident power P_in=5 μW emitted from a He-Ne laser, the rise time is 1 μs at a load resistance R_L 1 kΩ, and the excess noise factor is 6.53 at a multiplication M=48     

An Efficient Bulk‐Heterojunction Photovoltaic Cell Based on Energy Transfer in Graded‐Bandgap Polymers

It is demonstrated that the energy transfer from low‐conjugated (LC) poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene] (MEHPPV) to high‐conjugated (HC) MEHPPV, coupled with significant electron transfer from HC‐MEHPPV to an acceptor species, offers a viable route for an efficient photodiode over a wide spectral range. An enhanced incident‐photon‐to‐current conversion efficiency (IPCE) of 19 % over a wide spectral range and a power‐conversion efficiency (η_P) of 1 % (under monochromatic illumination at λ ～ 530 nm and a power density of ca. 1 mW cm^–2) are achieved in a ternary polymer‐blend film that consists of HC‐MEHPPV (low bandgap), LC‐MEHPPV (high bandgap), and an acceptor polymer, cyanoPPV (CNPPV), in an optimized ratio. The decisive role of the morphology that emerges during phase separation in the polymer blend is demonstrated by wide‐field photocurrent imaging.     

单片集成光电探测器与接收机的协同设计

建立了光电探测器的行为模型.此模型描述了注入光功率与光生电流的关系,以及反偏电压对光生电流与结电容的影响.给出了在统一的SPICE设计环境中对光电子器件与电路协同设计的方法,并对光电探测器与CMOS接收机电路进行了设计.     

单片集成光电探测器与接收机的协同设计

建立了光电探测器的行为模型.此模型描述了注入光功率与光生电流的关系,以及反偏电压对光生电流与结电容的影响.给出了在统一的SPICE设计环境中对光电子器件与电路协同设计的方法,并对光电探测器与CMOS接收机电路进行了设计.     

Photoconductive properties of organic-inorganic Ag/p-CuPc/n-GaAs/Ag cell

A thin film of copper phthalocyanine(CuPc),a p-type semiconductor,was deposited by thermal evaporation in vacuum on an n-type gallium arsenide(GaAs) single-crystal semiconductor substrate.Then semitransparent Ag thin film was deposited onto the CuPc film also by thermal evaporation to fabricate the Ag/p-CuPc /n-GaAs/Ag cell.Photoconduction of the cell was measured in photoresistive and photodiode modes of operation. It was observed that with an increase in illumination,the photoresistance decreased in reverse bias while it increased in forward bias.The photocurrent was increased in reverse bias operation.In forward bias operation with an increase in illumination,the photocurrent showed a different behavior depending on the voltage applied.