On the energy distribution of interface states and their relaxation time and capture cross section profiles in Al/SiO 2/p-Si (MIS) Schottky diodes

Abstract

The energy distribution profile of the interface states ( N ss) and their relaxation time ( τ) and capture cross section ( σ p) of metal–insulator–semiconductor (Al/SiO 2/p-Si) Schottky diodes have been investigated by using the high–low frequency capacitance and conductance methods. The capacitance–voltage ( C– V) and conductance–voltage ( G/ω– V) characteristics of these devices were investigated by considering series resistance ( R s) effects in a wide frequency range (5 kHz–1 MHz.). It is shown that the capacitance of the Al/SiO 2/p-Si Schottky diode decreases with increasing frequency. The increase in capacitance especially at low frequencies results form the presence of interface states at Si/SiO 2 interface. The energy distributions of the interface states and their relaxation time have been determined in the energy range of (0.362- E v)–(0.512- E v) eV by taking into account the surface potential as a function of applied bias obtained from the measurable C– V curve (500 Hz) at the lowest frequency. The values of the interface state density ( N ss) ranges from 2.34 × 10 12 to 2.91 × 10 12 eV −1/cm 2, and the relaxation time ( τ) ranges from 1.05 × 10 −6 to 1.58 × 10 −4 s, showing an exponential rise with bias from the top of the valance band towards the mid-gap.