Metal-organic chemical vapor deposition of quasi-normally-off AlGaN/GaN field-effect transistors on silicon substrates using low-temperature grown AlN cap layers

摘要

Low-temperature AlN grown on AIGaN/GaN heterostructure in situ by metal-organic chemical vapor deposition is used as gate insulator and passivation layer to form quasi-normally-off field-effect transistors on 4 in. silicon substrate. The AlN layer not only increases the sheet carrier density and mobility, which results in the increase of the maximum drain current and transconductance, but also decreases gate leakage and current collapse. Simulated band diagrams indicate that only a small potential difference exists between the AlN surface barrier height and the AlN/AlGaN interface. We show that low-temperature grown AlN is effective in suppressing trapping effects and in improving device performance.