The current-voltage characteristics of n-type GaN Schottky diodes have been measured in the extrinsic region (that is, the temperature range of 100–300 K). The effective density of states in the conduction band decreases with decreasing temperature and is close to the electron concentration at 100 K, leading to a reduction in the energy difference between the conduction band minimum and Fermi level and an increase in the probability of tunneling. Therefore, changes in the effective density of states in the conduction band and the probability of tunneling at low temperature are responsible for the decrease of the barrier height and increase in the ideality factor on the basis of the thermionic emission model. The mechanism of forward current flow has been clearly established in this study, leading to the thermionic emission (thermionic field emission) interpretation of the I-V characteristics at 300 K (100 K).
