Interface States and Barrier Nonuniformity in Ni/SiO 2 / p ‐Si/Al Metal–Insulator–Semiconductor Structures at Low Temperatures

The present study investigates the influence of series resistance, interface states and barrier height inhomogeneities on the forward current–voltage (I–V) characteristics of a Ni/SiO 2 / p ‐Si/Al MIS diode over the temperature range of 290–65 K. Conventional thermionic emission analysis revealed an anomalous decrease in the apparent barrier height and a corresponding increase in the ideality factor with decreasing temperature. The forward I–V characteristics exhibit convergence at elevated bias voltages, while the series resistance exhibits zero temperature coefficient behavior. To explain these observations, the Gaussian distribution model of barrier height inhomogeneities was employed. Analysis of the apparent barrier height and ideality factor revealed two Gaussian distributions of barrier heights in the temperature ranges of 290–155 K and 140–65 K, with mean barrier heights of 1.07 and 0.50 eV and standard deviations of 0.144 and 0.043 eV, respectively. The modified Richardson plot further confirmed the presence of double Gaussian distribution and yielded Richardson constants close to the theoretical values of p ‐Si. In addition, interface state density, extracted from forward I–V characteristics was found to show strong dependence on surface‐state energy and temperature. These findings provide deeper insight into the interfacial properties and carrier transport mechanisms in Ni/SiO 2 / p ‐Si/Al MIS structures.