Pairs of electron-holes are produced in the space-charge region of a diode pn heterojunction as a result of an accelerated electron beam collisions having enough energy larger or equal (≤ ٥٠ kev). Due to the intrinsic electric field an electric current will flow (Electron beam induced current EBIC) in an appropriate external electric circiut. When an external forward electric field is applied an electric current IF will flow, helping in electron-hole which combination produc an additional cathodo-lumines-cence. the study of cothodolumines- cence intensity variations will give electronic properties and electric structure of the space - charge.