Dimensional quantization ina-Si:H quantum-well structures: The alloy model

The effect of dimensional quantization on the density of states in amorphous semiconductors is studied theoretically. The disorder is treated as a random potential with zero correlation length (``white noise''). The transition of the density of states from staircase to smooth behavior with increasing disorder is traced for high-energy electrons and it was found to occur at substantially smaller film thicknesses than in experimental data. The possibility of resolving this contradiction in other models of disorder is discussed.