CdTe/ZnS复合钝化层对长波碲镉汞器件性能的影响研究

Study of CdTe/ZnS composite passivation layer effect on the performance of LW HgCdTe device

采用CdTe/ZnS复合钝化技术对长波HgCdTe薄膜进行表面钝化,并对钝化膜生长工艺进行了改进。采用不同钝化工艺分别制备了MIS器件和二极管器件,并进行了SEM、C-V和I-V表征分析,研究了HgCdTe/钝化层之间的界面特性及其对器件性能的影响。结果表明,钝化工艺改进后所生长的CdTe薄膜更为致密且无大的孔洞,Cd Te/HgCdTe界面晶格结构有序度获得改善;采用改进的钝化工艺制备的MIS器件C-V测试曲线呈现高频特性,界面固定电荷面密度从改进前的1.67×1011cm^(-2)下降至5.69×1010 cm^(-2);采用常规钝化工艺制备的二极管器件在较高反向偏压下出现较大的表面沟道漏电流,新工艺制备的器件表面漏电现象获得了有效抑制。

LW HgCdTe thin films were passivated by CdTe/ZnS composite passivation layer, and the growth process of passivation films was improved. The MIS devices and photodiodes were fabricated by using different passivation process. The SEM, C-V and I-V measurement were used to analyze the interface characteristics and its effect on the performance of devices. The results show that the CdTe film grown by improved process is more compact and has no large hole, the lattice structure order degree of CdTe/HgCdTe interface is improved; The C-V curve of MIS device fabricated by improved passivation process reveals high frequency characteristics, and interface fixed charge layers density is decreased from 1.67×10^11 cm^-2 to 5.69×10^10 cm^-2. The photodiode with general process has large surface channel leakage current under high reverse bias voltage, whereas the surface leakage current of the device with new process is effectively suppressed.