Hg_(1-x)Cd_xTe长波光伏探测器的低频噪声研究

LOW-FREQUENCY NOISE OF Hg_(1-x)Cd_xTe LONG-WAVE PHOTOVOLTAIC DETECTOR

在同一Hg1-xCdxTe晶片上(x=0.217)制备了单层ZnS钝化和双层(CdTe+ZnS)钝化的两种器件,对器件的低频噪声和暗电流进行了测试.发现单层钝化的器件在反偏较高时具有较高的低频噪声,在对器件的暗电流拟合计算中发现,单层钝化的器件具有较大的表面隧道电流,而这正是单层钝化器件具有较高低频噪声的原因.并通过高分辨X射线衍射中的倒易点阵技术RSM(reciprocalspacemapping)研究了两种钝化对HgCdTe外延层晶格完整性的影响,发现单层ZnS钝化的HgCdTe外延层产生了大量缺陷,而这些缺陷正是单层钝化器件具有较高的低频噪声和表面隧道电流的原因.

The Hg1-xCdxTe photovoltaic detectors with x =0. 217 passivated by single ZnS layer ad dual （ CdTe ＋ ZnS） layers were fabricated in the same wafer. The fabricated devices were characterized by measurements of the diode low-frequency noise. The diode passivated by dual （ CdTe ＋ ZnS） layers show higher performance compared to diode passivated by the single ZnS layer at high reverse bias, and the modeling of diode dark current mechanisms indicate that the performance of the diode passivated by single ZnS is strongly affected by tunneling current related to the surface defects, which is responsible for the low frequency noise characteristics. By the analysis of X-ray reciprocal space map, it was found that the Qy direction broadening of HgCdTe epitaxial layer passivated by ZnS was wider than the CdTe ＋ ZnS, which confirmed the existence of defects in the surface of HgCdTe epitaxial layer passivated by ZnS.