Capacitance-frequency (C-f) and conductance-frequency (G-f) characteristics of Ir/n-InGaN Schottky diode as a function of temperature

We report on the capacitance-frequency (C-f) and conductance-frequency (G-f) characteristics of Ir/n-InGaN Schottky diode with various biases and at different temperature. Investigations reveal that the capacitance is almost independent of temperature up to a certain value of frequency but the capacitance decreases at high frequencies. The higher values of capacitance at low frequencies are ascribed to the excess capacitance resulting from the interface states in equilibrium with the n-InGaN that could follow the alternating current signal. It is noted from G-f plots, there are peaks and those may be due to interface states between Ir and n-InGaN. The interface state density Nss and relaxation time τ of the Ir/n-InGaN Schottky structure are determined from C-f characteristics. The interface states densities show a decrease with bias from the bottom of the conduction band towards the mid gap at different temperature. Experimental results reveal that the values of relaxation time are higher towards the low temperature. The frequency dependence of the Rs is attributed to the particular distribution density of interface states.