Electronic properties of irradiated semiconductors. A model of the Fermi level pinning

A theoretical model of a defect state with highest localization in a semiconductor crystal is suggested. This model can be used to calculate the steady-state position of the Fermi level in radiation-modified semiconductors and to estimate the barrier height in metal-semiconductor contacts and the energy-band offsets in semiconductor heterojunctions. It is shown that the deepest level in the band gap of each semiconductor corresponds to the above state. This level plays a role similar to that of the level of electronic chemical potential in a bulk imperfect semiconductor and at the interphase boundary. Numerical calculations of the energy position of the level under consideration in the band gaps of Group IV and III-V compound semiconductors were performed. (C) 2003 MAIK Nauka / Interperiodica.