Abstract
The interface states induced in metal-oxide-semiconductor (MOS) capacitors by 25-keV electron beam irradiation have been investigated as a function of gate bias and irradiation dose using deep level transient spectroscopy (DLTS). The results clearly reveal the existence of two types of defects. The first type introduces a flat continuum of levels throughout the Si band gap and is not affected by the MOS gate bias. Another type is created only when a positive bias is applied to the MOS gate during irradiation and accounts for an additional broadband of levels in the midgap region. The physical origin of the bias voltage effect on these levels is briefly discussed.