Comparison of interface state density in MIS structure deduced from DLTS and Terman measurements

Interface state impedance has been theoretically predicted to introduce spurious detailed structures in the trap density curves when determined by high-frequency C/V measurements (Terman method). This is experimentally demonstrated on irradiated MOS structures. Terman analysis of these MOS capacitors presents a peak in the trap density near the conduction band, while a flat continuum is found by deep level transient spectroscopy (DLTS). A numerical simulation shows that this discrepancy can be taken into account by the only interface state impedance effect.