针对碲镉汞光伏器件的暗电流随着物理面积增大而急剧增加, 研究了子像元结构在降低大面积短波碲镉汞光伏器件暗电流方面的有效性。发现子像元结构在室温下相比常规结构可以有效降低器件的暗电流, 但当温度降到 180 K时, 常规结构器件反而具有最小的暗电流, 经过分析认为是子像元边界处引入的表面漏电所致。如果器件的表面态密度和表面固定电荷过多, 会使得子像元边界在低温下引入表面隧穿电流和表面欧姆电流, 这些与边界有关的表面漏电会成为低温下暗电流的主要成分, 从而使子像元结构失去降低器件暗电流的优势。文章中同时给出了低温下子像元结构可以有效降低器件暗电流的条件, 并针对不同的子像元结构, 提出了漏电体积这一参量来评价不同结构子像元降低器件暗电流的效果。

Sub-pixel structures have been applied to reduce the dark current of HgCdTe photovoltaic detectors with a large photo sensitive area, and their effectiveness has been evaluated. It was found that the sub-pixel structures led to a smaller dark current than one large pixel structure at room temperature, but they result in a greater dark current at 180 K. The analysis showed that the larger dark current at 180 K for the sub-pixel structure was caused by a surface leakage current introduced through the periphery. The surface states and fixed charges present at the interface of the passivation layer and HgCdTe surface could introduce surface tunneling current and surface shunting current, and these periphery-related surface dark current could become dominant at low temperatures, which rendered the sub-pixel structure meaningless in reducing the dark current of the large area detectors. The requirements for using sub-pixel structures at low temperatures were also given, and the term “leakage current bulk” has been put forward to assess different sub-pixel structures when used to decrease the dark current.