Photodiode and array of photodiodes on II-VI material and their production processes. The photodiodes (48) are formed in a type P, Hg.sub.1-x Cd.sub.x Te semiconductor layer (13) with 0.ltoreq.x.ltoreq.1 deposited directly on a CdTe insulating substrate (11), having an active zone (37) of type N, a first electrical contact (47) on the semiconductor layer, a second electrical contact (45) on the active zone, and insulant (21) separating the first and second electrical contacts and an insulation or isolation trench (15), whose depth exceeds the thickness of the active zone and surrounding the latter, the first electrical contact (47) being located in the bottom (27) of the trench.