Role of electron injection on vertical leakage in GaN-on-Si epitaxial layers

The impact of electron injection on vertical leakage current of GaN-on-Si epitaxial layers with an AlN interlayer has been investigated. At high electric field, the AlN interlayer as an energy barrier can suppress the injection of electrons from the silicon substrate into the top buffer layers, and eventually a vertical leakage was reduced by two orders of magnitude at 600 V. At low electric field, the holes flow via dislocations, and prevent the formation of a negative depletion region at the top GaN layer increasing the leakage. The correlation between the vertical leakage and the buffer-related trapping has also been clarified by ramped back-gating characterizations.