Localised defect-induced Schottky barrier lowering in n-GaN Schottky diodes

The forward bias current–voltage (I–V) characteristics of n-GaN Schottky diodes on sapphire substrate were investigated over a wide temperature range of 70–500 K. For models based on localised regions of lowered Schottky barrier height, a distributed barrier height should be expected when these localised regions are comparable to or smaller in size than the depletion width. However, a suitable fit for the I–V curves, which exhibited anomalous two-step (kink) forward bias behaviour, was only obtained when modelling the leakier regions with a single reduced barrier height, by using a model of two discrete diodes in parallel.