Abstract
The density of states (DOS) has been measured at room temperature for undoped a-Si: H by means of a temperature-modulated space-charge-limited currents (TM-SCLC) method in an annealed state A and after prolonged illumination—state B. With increasing illumination time the peak in the DOS at E - E C = 0·61 eV grows, and we attribute this to the D-Si dangling bond level. From the difference in the position of this D level and the stable Fermi level in state B (E F - E C = 0·79 eV) we deduce that the effective correlation energy of Si dangling bond in undoped a-Si: H is U eft = +0·36 ± 0·03 eV.