Processing of LPE-Grown HgCdTe for MWIR Devices Designed for High Operating Temperatures

摘要

Significant improvements of HgCdTe (MCT) detectors for the midwave infrared (MWIR) region with cutoff wavelength of about 5.2 μm at 77 K have been achieved. Optimizing the CdTe passivation proved to be a decisive step towards higher operating temperatures. The optimization was done by refining the interdiffusion process of the CdTe passivation layer with the liquid phase epitaxy-grown layer. The dark current density was reduced almost to the level of Rule 07, a common infrared detector benchmark. Additionally, improving the passivation process also decreased tunneling. These advancements also showed up in the focal-plane array (FPA) performance. A considerable reduction of the noise-equivalent temperature difference at temperatures above 130 K was attained. Based on these preliminary results, an operating temperature for these devices of more than 160 Kis expected. Additionally, infrared (IR) pictures taken with a MWIR MCT-based FPA processed with the previous, slightly improved technology are presented. It is shown that good picture quality is attained at operating temperature of 140 K while retaining operability of 99.61%.