为研究光伏探测器瞬态响应特性在短脉冲激光作用下的变化规律, 以一种室温下零偏压工作的HgCdTe光电二极管为实验对象, 测量了该器件对脉冲宽度约16 ns的不同强度响应波段内激光的响应信号波形。在探测器的对数线性响应区内, 随着入射激光能量密度从约7.2 nJ/cm2增大到75 μJ/cm2, 响应波形的宽度逐渐增大, 半高宽约由55 ns增大到235 ns, 底宽约由170 ns增大到380 ns。脉冲响应波形的展宽意味着器件的瞬态响应特性发生了退化。通过分析强注入条件下光电二极管准中性区光生载流子扩散过程, 以及结电场与结电容变化对过剩载流子输运过程的影响, 对上述光伏探测器瞬态响应特性退化的特征进行了机理解释。

In order to investigate the transient response characteristics of photovoltaic detectors irradiated by short-pulse laser, the response waveforms of a HgCdTe photodiode to laser pulses with 16 ns duration and different laser intensities were measured. The photodiode worked with room temperature and zero bias, and the laser wavelength was in the response spectrum of the photodiode. In the detector′s linearly logarithmic response zone, the signal waveform broadened gradually with the incident laser energy density from 7.2 nJ/cm2 to 75 μJ/cm2. The full width at half maximum of signal waveform rose to 235 ns from 55 ns, at the same time the bottom width rose to 380 ns from 170 ns. The pulse response broadening of the detector implied degradation of its transient response characteristics. The mechanism of the response degradation was explained via analysis on the diffusion process of photocarriers in the quasineutral region and on the changes of junction electric field and junction capacitance under high-injection condition.