Surface Treatment Method of Near-Stoichiometric Ratio HgCdTe Film

Surface components of HgCdTe (MCT) films were examined using x-ray photoelectron spectroscopy after etching with different solutions, including Br₂:methanol (Br₂:Me), Br₂:HBr, and Br₂:HBr:ethanediol (Br₂:HBr:Eg). The surface degradation after etching by bromide-based solutions arises from the Te-rich element on the surface of HgCdTe, and the enrichment degree of Te is (Br₂:HBr:Eg) < (Br₂:HBr) < (Br₂:Me). The wet-etch method is difficult to apply in eliminating Te-rich components to achieve a near-stoichiometric surface. In the commonly used method, oxidation is followed by corrosion. Plasma oxidation offers advantages, such as strong oxidation, stability, safety, and environmental protection. Therefore, oxygen plasma treatment has been introduced for various etchants to eliminate oxides, including hydrochloric acid, lactic acid, and ammonia. The results indicate that the use of low-concentration hydrochloric acid immersion generates a better effect without introducing any new dopants, and the defect density of the CdTe/HgCdTe interface decreases significantly after treatment.