Temperature-dependent current–voltage and capacitance–voltage characteristics of the Ag/n-InP/In Schottky diodes

Abstract

The current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Ag/n-InP/In Schottky diodes have been studied in a wide temperature range by steps of 10 K. A decrease in the apparent barrier height (BH), \(\Upphi_{bo}\), an increase in the ideality factor, \(n\) and a nonlinearity in the activation energy plot with a decrease in temperature have been seen. The experimental values of BH and ideality factor for the devices were calculated as 0.61 eV and 1.18 at 320 K, 0.48 eV and 1.52 at 200 K, and 0.20 eV and 3.89 at 70 K, respectively. An abnormal decrease in the experimental BH \(\Upphi_{b}\) and an increase in the ideality factor n with a decrease in temperature have been explained by the barrier inhomogeneities at the metal–semiconductor (MS) interface. From the temperature dependent I–V characteristics of the Ag/n-InP contact, that is, \(\overline{\Upphi}_{bo}\) and A* as 0.79 and 0.55 eV, and 7.96 and \(8.18\,\hbox{A/cm}^{2}\hbox{K}^{2}\), respectively, have been calculated from a modified \(\hbox{ln}(I_{0}/T^{2})-q^{2}\sigma _s^2/2k^{2}T^{2}\) vs. 1/T plot for the two temperature regions. The Richardson constant values are in close agreement with the value of \(9.8\,\hbox{A/cm}^{2}\hbox{K}^{2}\) known for n-type InP. Moreover, the difference between the apparent BHs obtained from the I–V and C–V characteristics has been attributed to the existence of Schottky BH inhomogeneity.