Incomplete space-charge layers in semiconductors

Analysis of the potential and field profiles in space-charge layers near semiconductor interfaces is extended to consider cases in which the thickness of the semiconductor layer is less than the conventional ‘‘width’’ of the space-charge region that would exist if the semiconductor were very thick. It is shown that both electrostatic effects and possible Fermi-level changes are important in these cases. The apparent deficiency of charge that such thin layers present is found to be illusory; adequate charge is always available. However, the process which provides this charge may alter the work function of the semiconductor and therefore change the potential distribution.