Electrical properties and the determination of interface state density from I–V, C–f and G–f measurements in Ir/Ru/n-InGaN Schottky barrier diode

Abstract

The electrical properties of the Ir/Ru Schottky contacts on n-InGaN have been investigated by current-voltage (I–V), capacitance-voltage (C–V), capacitance-frequency (C–f) and conductance-frequency (G–f) measurements. The obtained mean barrier height and ideality factor from I–V are 0.61 eV and 1.89. The built-in potential, doping concentration and barrier height values are also estimated from the C–V measurements and the corresponding values are 0.62 V, 1.20 × 1017 cm^–3 and 0.79 eV, respectively. The interface state density (N_SS) obtained from forward bias I–V characteristics by considering the series resistance (R_S) values are lower without considering the series resistance (R_S). Furthermore, the interface state density (N_SS) and relaxation time (τ) are also calculated from the experimental C–f and G–f measurements. The N_SS values obtained from the I–V characteristics are almost three orders higher than the N_SS values obtained from the C–f and G–f measurements. The experimental results depict that N_SS and τ are decreased with bias voltage. The frequency dependence of the series resistance (R_S) is attributed to the particular distribution density of interface states.