SEMICONDUCTOR DEVICE

摘要

Thick undoped layers (22) with thicknesses of, for instance, about 50nm and thin n-type doped layers (23) thin enough (for instance about 10nm) to exhibit a quantum effect are alternated on a substrate (3) made of SiC, GaN, or GaAs to form an active region (30). Carriers are distributed from sub-bands produced by the quantum effect of the n-type doped layers (23) to the undoped layers (22). Since the impurity scattering is reduced in the undoped layers (22) which contain fewer impurities, a high carrier mobility can be achieved. By utilizing the fact that the carries disappear from the active region (30) when the whole active region (30) is depleted, a high dielectric strength can be achieved by the undoped layers (22).