EFFECT OF INSIDE-SPREAD SURFACE-STATES ON FERMI LEVEL PINNING

The potential distribution in the space charge zone when bulk electronic states are present is calculated. This is used to quantitatively examine the hypothesis that surface states responsible for the Fermi level pinning on III-V materials are spread over several angstrom inside the semiconductor. They are called inside-spread surface states due to the nature of their origin. It is found that variations in the penetration depth of the states, when at least one donor-acceptor pair is present, can explain for the most part the experimental behaviour. When both true-surface and inside-spread states are present, it is found that the ones closest to the interior generally accounts for the Schottky barrier height (even more so when their density and/or their penetration depth are high). To conclude, the hypothesis that surface states can penetrate into the semiconductor should be considered in any attempt to explain pinning position movement. © 1990.