SEMICONDUCTOR PHOTO DETECTOR

PURPOSE:To obtain a highly efficient detector in a very long wavelength band capable of easy incidence into a quantum well layer by securing sensitivity regardless of electric field direction of incident light, when the light is made to enter parallel with a substrate. CONSTITUTION:A quantum well layer 2 is formed on two inclined surfaces which are formed on a substrate 1 and intersect with each other. Since the directions of electron dipoles on the inclined surfaces A and B are different with each other the incident light can be absorbed on the inclined surface A or B, whichever direction the electric field of the light faces to. When the transition of electron in the quatum well between quantized levels is considered, the direction of electron dipole becomes vertical to the quantum well layer. When the light enters vertically to the quantum well layer, light absorption is not caused, because the electric field vector makes right angles with the incidence direction. In order to couple the light with the dipole in the case of vertical incidence, the electron well layer is necessary to be inclined to the crystal surface. That is, substrate crystal is processed and turned into an inclined surface, on which a quantum layer may be grown.