Photo-Enhanced Native Oxidation Process for Hg_0.8Cd_0.2Te Photoconductors

The aim of this paper is to propose an easy and reproducible vapor-phase photo surface treatment method to improve the device performance of the Hg_0.8 Cd_0.2Te photoconductive detector. We explore the effect of surface passivation on the electrical and optical properties of the HgCdTe photoconductor. Experimental results, including surface mobility, surface carrier concentration, metal-insulator-semicotiductor leakage current, 1/f noise voltage spectrum, the 1/f knee frequency, responsivity R_λ, and specific detectivity D* for stacked photo surface treatment and ZnS or CdTe passivation layers are presented. These data are all directly related to the quality of the interface between the passivation layer and the HgCdTe substrate. We found that, by inserting a photo native oxide layer, we can shift the 1/f knee frequency, reduce the noise power spectrum, and achieve a lower surface recombination velocity S. A higher D* can also be achieved. It was also found that HgCdTe photoconductors passivated with stacked layers show improved interface properties compared to the photoconductors passivated only with a single ZnS or CdTe layer.