Effects of barrier height distribution on the behavior of a Schottky diode

The current–voltage characteristics of a Schottky diode are simulated numerically using the thermionic emission-diffusion mechanism and considering a Gaussian distribution of barrier heights, with a linear bias dependence of both the mean and standard deviation. The resulting data are analyzed to get insight into the effects of distribution parameters on the barrier height, activation energy plots and the ideality factor over a temperature range 50–300 K. It is shown that with a Gaussian distribution of the barrier heights the system continues to behave like a single Schottky diode of apparently low zero-bias barrier height and a high ideality factor. Its barrier height decreases, activation energy plot becomes non-linear and ideality factor increases with a decrease in temperature. While the distribution parameters are responsible for the abnormal decrease of barrier height, their bias dependences account for the higher ideality factor at low temperatures. Also, the pivotal role played by series resistance in influencing the linearity of the ln$\mathrm{(I)–V}$ plots of Schottky diodes with a Gaussian distribution of barrier heights is discussed.