CdTe is deposited by electron-beam evaporation on the bulk $Hg_{1-x}Cd_xTe$ with x=0.22 and x=0.30. The insulating property of CdTe film is adequate to isolate $Hg_{1-x}Cd_xTe$ substrate from metal pads if it were deposited as slowly as the rate of 30Å/$\min$. Electrical properties of the CdTe/$Hg_{1-x}Cd_xTe$ passivation are determined by capacitance-voltage and current-voltage measurement of metal-insulator-semiconductor(MIS) test devices. We make the MIS structures of CdTe monolayer and CdTe/ZnS double layer as insulator. Although flat-band condition is achieved, Δ$V_{FB}$ is as large as 1V∼2V showing huge insulator trapped-charge density. To clean the freshly Br-MeOH etched $Hg_{1-x}Cd_xTe$ surface, in-situ ultraviolet(UV) photon-assisted hydrogen radicals pretreatment is done. And it improves the CdTe film quality to reduce Δ$V_{FB}$. The infrared photodiodes using e-beam CdTe as passivant is fabricated to show excellent characteristics.
