Forward Current Transport Mechanisms of Ni/Au-InAlN/AlN/GaN Schottky Diodes

We fabricate two Ni/Au-In0.17 Al0.83N/AlN/GaN Schottky diodes on substrates of sapphire and Si, respectively, and investigate their forward-bias current transport mechanisms by temperature-dependent current-voltage mea- surements. In the temperature range of 300-485K, the Schottky barrier heights （SBHs） calculated by using the conventional thermionic-emission （TE） model are strongly positively dependent on temperature, which is in contrast to the negative-temperature-dependent characteristic of traditional semiconductor Schottky diodes. By fitting the forward-bias I V characteristics using different current transport models, we find that the tunneling current model can describe generally the I V 5ehaviors in the entire measured range of temperature. Under the, high forward bias, the traditional TE mechanism also gives a good fit to the measured I-V data, and the actual barrier heights calculated according to the fitting TE curve are 1.434 and 1.413eV at 300K for InAlN/AlN/GaN Schottky diodes on Si and the sapphire substrate, respectively, and the barrier height shows a slightly negative temperature coefficient. In addition, a formula is given to estimate SBHs of Ni/Au-InAlN/AlN/GaN Schottky diodes taking the Fermi-level pinning effect into account.