Analysis of the current-voltage characteristics of the Pd/Au Schottky structure on n-type GaN in a wide temperature range

We report on the temperature-dependent electrical characteristics of the Au/Pd/ n-GaN Schottky diode in the temperature range of 90-410 K. The barrier heights and ideality factors of Schottky diodes were found in the range 0.23 eV and 3.5 at 90 K to 0.97 eV and 1.9 at 410 K, respectively. It was observed that the zero bias barrier height Phi(bo) decreases and the ideality factor n increases with a decrease in temperature. Such behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. The estimated values of series resistance (RS) are in the range of 636 Omega at 90 K to 220 Omega at 410 K using Cheung's method. Based on the above observations, the Phi(bo), n and RS values are seen to be strongly temperature dependent. The flat-band barrier height Phi(bf) (T = 0 K) and temperature coefficient a were found to be 0.67 eV and 2.81 x 10(-3) eV K-1, respectively. Further, the homogeneous barrier height is estimated from the linear relationship between temperature-dependent experimental effective barrier heights and ideality factors and the value is approximately 1.31 eV. The effective Richardson constant is determined to be 20.43 A cm(-2) K-2 and is in good agreement with the theoretical value. It is concluded that the temperature-dependent I-V characteristics of the Au/Pd/ n-GaN Schottky diode can be successfully explained on the basis of thermionic emission (TE) mechanism with the Gaussian distribution of the barrier heights.