γ辐照导致中波碲镉汞光伏器件暗电流退化的机理研究

Study on the mechanism of dark current degradation of HgCdTe photovoltaic devices induced by γ-irradiation

针对红外探测器在空间应用中受到高能粒子辐照后暗电流退化的问题,开展γ射线对中波碲镉汞(HgCdTe)光伏器件暗电流影响的研究。在室温和77 K温度下,利用60Co-γ射线对HgCdTe器件进行辐照试验,辐照试验结束后对低温辐照器件进行77 K低温退火和室温退火。通过比较γ辐照前后和退火后器件的I-V特性、R-V特性和零偏动态电阻R0参数,分析了γ辐照对HgCdTe器件暗电流的影响机制。试验结果表明:在总剂量为7 Mrad(Si)照条件下,器件暗电流未出现明显的退化;在77 K温度辐照条件下,器件暗电流随着总剂量的增加而增加,且暗电流退化幅度与辐照过程中的偏置有关。研究表明暗电流的退化源于γ辐照在器件中造成电离损伤,导致器件HgCdTe化层中的界面态和空穴陷阱电荷密度增加。

Aiming at the problem that the infrared detector is degraded by the high-energy particle irradiation in the space application,the effect ofγ-ray on the dark current of the medium-wave HgCdTe photovoltaic device was studied.The HgCdTe device was irradiated with 60 Co-γrays at room temperature and 77 K.After the irradiation test,the low temperature irradiated device was subjected to77 K low temperature annealing and room temperature annealing.By comparing the I-V characteristics,R-V characteristics and zero-bias dynamic resistance R0 parameters of the device before and after irradiation,the influence mechanism ofγ-irradiation on the dark current of the HgCdTe device was analyzed.The test results show that the dark current of the device does not show obvious degradation after irradiation at room temperature under the total dose of 7 mrad(Si).Under 77 K temperature irradiation conditions,the dark current of the device increases with the dose,and the dark current degradation amplitude is related to the bias during the irradiation test.Studies have shown that the degradation of dark current was caused by gamma irradiation causing ionization damage in the device,resulting in an increase in the interface state and hole trap charge density in the device’s CdTe passivation layer.