Backside-electrode effects on current collapse in field-plate AlGaN/GaN HEMTs

Two-dimensional transient analysis of field-plate AlGaN/GaN HEMTs with a backside electrode is performed by considering the use of a deep donor and a deep acceptor in a buffer layer. Effects of introducing the field plate and backside electrode on buffer-related current collapse are studied. It is shown that the introduction of field plate is effective in reducing current collapse when the acceptor density in the buffer layer is high. On the other hand, the introduction of backside electrode is shown to be effective in reducing current collapse when the acceptor density in the buffer layer is relatively low, because the fixed potential at the backside electrode reduces electron injection into the buffer layer and the resulting trapping effects.