Interface capacitance in metal-semiconductor junctions

Abstract

A new theory of the interface capacitance at metal-semiconductor junctions is presented. The diode capacitance is attributed to the modulation of the effective Schottky barrier height by interface charge. Relations between the measured capacitance and the physical properties of the interface states are formulated by using Shockley-Read statistics and taking into account the electron relaxation-time dispersion. This theory is applied to NiSi 2-nSi diodes with both epitaxial and nonepitaxial interfaces. Spectra of density distribution, as well as other interface parameters, are obtained, indicating that interface states in these diodes are most probably defect related.