Current collapse and the role of carbon in AlGaN/GaN high electron mobility transistors grown by metalorganic vapor-phase epitaxy

The two deep traps responsible for current collapse in AlGaN/GaN high elect ron mobility transistors grown by metalorganic vapor-phase epitaxy have bee n studied by photoionization spectroscopy. Varying the growth pressure of t he high resistivity GaN buffer layer results in a change in the deep trap i ncorporation that is reflected in the observed current collapse. Variations in the measured trap concentrations with growth pressure and carbon incorp oration indicate that the deepest trap is a carbon-related defect, while th e mid-gap trap may be associated with grain boundaries or dislocations. (C) 2001 American Institute of Physics.