JPS628957B

PURPOSE:To obtain a monolithic light detector element of optional cut-off wavelength, by establishing regions of different band gaps in a compound semiconductor substrate and providing light detection portions at optional places on the regions. CONSTITUTION:A p-type Hg1-xCdxTe layer 11 is grown on a CdTe substrate 10 by a gas phase epitaxial growing method. The layer 11 is obliquely polished so that its thickness is straightly varied. The entire surface of the layer 11 is coated with a thin insulating film 17 of ZnS, SiO2 or the like. An opening is perforated through the film 17. The exposed part of the layer 11 is changed into n-type regions 12-14 by heat treatment under an atmosphere of Hg, proton irradiation or implantation of ions of Hg, Al or the like. The mixture ratios of these regions 12-14 are related to one another as x1