Radiation-sensitive semiconductor device

A radiation sensitive semiconductor device comprising a semiconductor body having a substrate, an epitaxial semiconductor layer on said substrate and having a substantially flat surface exposed to radiation during operation, the resistivity of said semiconductor layer being between about 50-200 ohm.cm and the resistivity of said substrate being substantially less than 50 ohm.cm, at least one radiation-sensitive element at said surface, said radiation-sensitive element comprising at least two radiation-sensitive sub-elements forming rectifying junctions with said semiconductor layer, means for separately applying a reverse bias to said rectifying junctions of each of said sub-elements, the distance between adjacent sub-elements and the thickness of said semiconductor layer being so small that in operation the depletion regions associated with said rectifying junctions extend in a lateral direction parallel to said surface so as to merge, and extend in a vertical direction perpendicular to said surface so as to deplete said semiconductor layer over the greater part of its thickness, the lateral distance between adjacent sub-elements being at most equal to twice the thickness in the lateral direction of the depletion region located laterally adjacent and associated with each sub-element during operation, each of said radiation-sensitive sub-elements comprising means for detecting a current through said sub-element generated by radiation impinging on said surface, and the surface area between adjacent radiation-sensitive sub-elements and the major part of each of said sub-elements being accessible to said radiation.