Abstract: Cd-rich polycrystalline Hg_1-xCdx.Te was electrodeposited on a Ti substrate from anacidic solution(pH=1.0)of mixture of 0.2mol/L CdSO₄, 5?10^-4mol/L TeO₂ and 1.13?10^-5 mol/L HgCl₂. The film has a cubic structure with preferential orientation in(111).Thevalue of 1-x in Hg_1-xCdxTe was determined by EDAX to be 0.09. The photoelectro-chemical cell has a solar energy conversion efficiency of about 0.43% under AM1. 5 illu-mination in a polysulfide redox solution(1.0mol/L Na₂S+0.2mol/L S+1.0mol/L NaOH).The bandgap of Hg_0.09Cd_0.91Te was about 1.26eV.

Key words: Photoelectrochemistry, polycrystalline thin film, mercury cadmium telluride