短波红外InGaAs焦平面噪声特性

Noise characteristics of short wave infrared InGaAs focal plane arrays

为研究铟镓砷焦平面的噪声特性,设计了两种不同吸收层掺杂浓度的InGaAs外延材料,采用标准工艺制备了平面型160×128元光敏芯片,并与相同结构的读出电路倒焊耦合形成160×128元焦平面,采用改变积分时间和改变器件温度的方法,测试焦平面的信号与噪声.通过研究不同材料参数、器件性能与焦平面噪声的关系,定量分析了短波红外InGaAs焦平面的噪声特性.结果表明,焦平面噪声主要来源于焦平面耦合噪声和探测器噪声,降低InGaAs外延材料吸收层的掺杂浓度,可以有效降低探测器电容,从而降低焦平面的耦合噪声;而探测器噪声由探测器暗电流和工作温度影响,该噪声在长积分时间下决定了焦平面的总噪声水平.实现低暗电流、低电容特性的光敏芯片是降低焦平面噪声的有效途径.

In order to study the noise characteristics of InGaAs focal plane arrays (FPAs), the 160×128 FPAs with different absorption layer doping concentration coupled with the same read-out circuit structures were designed and prepared. The noise characteristics at different temperature and integral time were measured. By studying the relationship between different material parameters, device performance and focal plane noise, the noise characteristics of short-wave infrared InGaAs FPAs are analyzed quantitatively. The results show that the noise mainly comes from the coupling noise of the focal plane and the noise of the detector. The detector noise is influenced by the dark current and operating temperature of the detector, which determines the total noise level of the focal plane in the long integral time. To manufacture photodetectors with low dark current and low capacitance is an effective way to reduce the focal plane noise.