Effect of measurement frequency on admittance characteristics in Al/p-Si structures with interfacial native oxide layer

Abstract

Al/p-Si/Al diodes with interfacial native oxide layer were formed. Their frequency induced admittance-voltage measurements were made. The frequency-dependent density distribution of interface states has been determined from the corrected characteristics by considering the series resistance effect which masks the interface trap loss. The majority carrier density corresponding to the depletion and inversion parts of the C-2-V curve, was determined 1.82 x 1014 and 4.48 x 1014 cm-3 at 1000 kHz, respectively. The fact that the carrier density obtained from the inversion part of the plot is higher than that obtained from the depletion part can be related to the increase in the density of negative space charge in the depletion region.The value of was determined as 0.95 eV from the same plot. Interface state density decreased from 4.31 x 1012 eV-1cm-2 at 100 kHz to 7.30 x 1011 eV-1 cm-2 at 1000 kHz, because the interface charges do not follow the ac signal and do not contribute to capacitance values in high frequencies.