Quantum well intermixing techniques modify the geometric shape of quantum wells to allow postgrowth adjustments.The tuning effect on the optical response property of a GaAs/AlGaAs quantum well infrared photodetector(Q...Quantum well intermixing techniques modify the geometric shape of quantum wells to allow postgrowth adjustments.The tuning effect on the optical response property of a GaAs/AlGaAs quantum well infrared photodetector(QWIP) induced by the interdifussion of Al atoms was studied theoretically.By assuming an improvement of the heterointerface quality and an enhanced Al interdiffusion caused by postgrowth intermixings,the photoluminescence spectrum shows a blue-shifted,narrower and enhanced photoluminescence peak.The infrared optical absorption spectrum also shows the expected redshift of the response wavelength.However,the variation in the absorption peak intensity depends on the boundary conditions of the photo generated carriers.For high-quality QWIP samples,the mean free path of photocarriers is long so that the photocarriers are largely coherent when they transport across quantum wells.In this case,the enhanced Al interdiffusion can significantly degrade the infrared absorption property of the QWIP.Special effects are therefore needed to maintain and/or improve the optical properties of the QWIP device during postgrowth treatments.展开更多
Standard GaAs/AlGaAs quantum well infrared photodetectors(QWIP)have been seriously considered as atechnological choice for the 3^(rd) generation of thermal imagers in the long wave infrared band(LWIR)for some time.Alt...Standard GaAs/AlGaAs quantum well infrared photodetectors(QWIP)have been seriously considered as atechnological choice for the 3^(rd) generation of thermal imagers in the long wave infrared band(LWIR)for some time.Alternative technology like MCT(HgCdTe)was the technology choice of the 2^(nd) generation because of its high quantum efficiency.In the paper,measurements on the QWIP technology will be presented and a comparison with alternative technology will be done.展开更多
为提高势垒型中波InAs/InAsSb二类超晶格红外探测器器件性能,研究并设计了nBn势垒型InAs/InAsSb器件结构。针对InAs/InAsSb红外探测器器件结构特征,分析了暗电流的主导机制和能带特性,采用基于泊松方程、连续性方程和热方程的数值计算方...为提高势垒型中波InAs/InAsSb二类超晶格红外探测器器件性能,研究并设计了nBn势垒型InAs/InAsSb器件结构。针对InAs/InAsSb红外探测器器件结构特征,分析了暗电流的主导机制和能带特性,采用基于泊松方程、连续性方程和热方程的数值计算方法,通过精确调控吸收层掺杂、势垒层掺杂、势垒层厚度、温度和组分等,构建出高能量势垒以有效阻挡多数载流子,允许少数载流子迁移,实现价带偏移(Valence Band Offset,VBO)接近于零的要求,从而有效降低暗电流。研究结果表明,在1×10^(15)~1×10^(17)cm^(-3)范围内降低势垒层掺杂浓度,VBO和暗电流开启电压绝对值均会减小,当AlAs1-xSbx势垒中Sb组分为0.91时,VBO接近于零。对于吸收层,随着掺杂浓度的提高,暗电流呈现减小趋势,但趋势较不明显。在-0.5V偏压,140 K工作条件下,吸收层和势垒层掺杂浓度分别为1×10^(13)cm^(-3),1×10^(15)cm^(-3),吸收层与势垒层厚度分别为3μm,80 nm,得到器件结构参数优化后的暗电流低至4.5×10^(-7)A/cm^(2),证明InAs/InAsSb中波红外探测器具有高温工作的应用前景,可广泛应用于导弹预警、红外制导、航空航天等领域。展开更多
随着高工作温度红外光电子器件的发展,更高的工作温度下,冷屏部件的热辐射会带来背景辐射噪声,对红外探测器的成像造成干扰。为研究高温器件冷屏部件热辐射对芯片性能的影响,基于蒙特卡洛原理,采用3D Studio Max建立冷屏模型,提取模型...随着高工作温度红外光电子器件的发展,更高的工作温度下,冷屏部件的热辐射会带来背景辐射噪声,对红外探测器的成像造成干扰。为研究高温器件冷屏部件热辐射对芯片性能的影响,基于蒙特卡洛原理,采用3D Studio Max建立冷屏模型,提取模型信息编写程序,计算冷屏部件各部分对芯片的辐射传递因子,进而得到冷屏部件热辐射在芯片上产生的噪声信号。在给定的参数和条件下,对某高温器件冷屏进行计算分析,表明该高温器件冷屏部件的温度需低于196 K。为抑制高温器件冷屏部件的热辐射,研究了整体降低冷屏发射率和局部降低冷屏发射率这两种方案。整体降低冷屏发射率可降低冷屏自身热辐射产生的噪声信号,但会造成外部辐射中经冷屏反射间接到达芯片的杂散辐射噪声信号迅速增加。局部降低冷屏发射率可降低冷屏自身热辐射产生的噪声信号并使外部辐射中经冷屏反射间接到达芯片的杂散辐射噪声信号缓慢增加。采用局部降低冷屏发射率的方案,对总的杂散辐射的抑制效果与温度有关,当冷屏部件温度小于203 K时,会引起总的杂散辐射噪声信号增加;当冷屏部件温度大于203 K时,可以降低总的杂散辐射噪声信号。展开更多
介绍了多波段红外探测器的应用开发进展,并且针对多波段信号同时探测的红外器件特点进行了读出电路设计。其中,Pixel输入级为多波段红外探测器读出电路设计的核心关键模块之一。本文设计采用了缓冲直接注入型(Buffered Direct Injection...介绍了多波段红外探测器的应用开发进展,并且针对多波段信号同时探测的红外器件特点进行了读出电路设计。其中,Pixel输入级为多波段红外探测器读出电路设计的核心关键模块之一。本文设计采用了缓冲直接注入型(Buffered Direct Injection,BDI)像素输入级电路结构,具有高稳定性、低等效输入阻抗的特点,有效提高长波器件的注入效率,并且为光电探测器件提供了稳定的工作条件。以CMOS 0.18μm 5 V标准工艺基础,完成了全电路设计与模拟仿真。结果表明:70 K低温下电路功能正常,40μm间距内含有短、中、长4波段像素输入级,输入级积分信号输出线性度达到99.7%,噪声不超过0.3 mV。展开更多
文摘Quantum well intermixing techniques modify the geometric shape of quantum wells to allow postgrowth adjustments.The tuning effect on the optical response property of a GaAs/AlGaAs quantum well infrared photodetector(QWIP) induced by the interdifussion of Al atoms was studied theoretically.By assuming an improvement of the heterointerface quality and an enhanced Al interdiffusion caused by postgrowth intermixings,the photoluminescence spectrum shows a blue-shifted,narrower and enhanced photoluminescence peak.The infrared optical absorption spectrum also shows the expected redshift of the response wavelength.However,the variation in the absorption peak intensity depends on the boundary conditions of the photo generated carriers.For high-quality QWIP samples,the mean free path of photocarriers is long so that the photocarriers are largely coherent when they transport across quantum wells.In this case,the enhanced Al interdiffusion can significantly degrade the infrared absorption property of the QWIP.Special effects are therefore needed to maintain and/or improve the optical properties of the QWIP device during postgrowth treatments.
文摘Standard GaAs/AlGaAs quantum well infrared photodetectors(QWIP)have been seriously considered as atechnological choice for the 3^(rd) generation of thermal imagers in the long wave infrared band(LWIR)for some time.Alternative technology like MCT(HgCdTe)was the technology choice of the 2^(nd) generation because of its high quantum efficiency.In the paper,measurements on the QWIP technology will be presented and a comparison with alternative technology will be done.
文摘为提高势垒型中波InAs/InAsSb二类超晶格红外探测器器件性能,研究并设计了nBn势垒型InAs/InAsSb器件结构。针对InAs/InAsSb红外探测器器件结构特征,分析了暗电流的主导机制和能带特性,采用基于泊松方程、连续性方程和热方程的数值计算方法,通过精确调控吸收层掺杂、势垒层掺杂、势垒层厚度、温度和组分等,构建出高能量势垒以有效阻挡多数载流子,允许少数载流子迁移,实现价带偏移(Valence Band Offset,VBO)接近于零的要求,从而有效降低暗电流。研究结果表明,在1×10^(15)~1×10^(17)cm^(-3)范围内降低势垒层掺杂浓度,VBO和暗电流开启电压绝对值均会减小,当AlAs1-xSbx势垒中Sb组分为0.91时,VBO接近于零。对于吸收层,随着掺杂浓度的提高,暗电流呈现减小趋势,但趋势较不明显。在-0.5V偏压,140 K工作条件下,吸收层和势垒层掺杂浓度分别为1×10^(13)cm^(-3),1×10^(15)cm^(-3),吸收层与势垒层厚度分别为3μm,80 nm,得到器件结构参数优化后的暗电流低至4.5×10^(-7)A/cm^(2),证明InAs/InAsSb中波红外探测器具有高温工作的应用前景,可广泛应用于导弹预警、红外制导、航空航天等领域。
