Physics-based simulation of back-electrode effects on lag and current collapse in field-plate AlGaN/GaN HEMTs

Two-dimensional transient analysis of gate-field-plate AlGaN/GaN HEMTs with a backside electrode is performed by considering a deep donor and a deep acceptor in a buffer layer. It is shown that the introduction of gate field plate is effective in reducing buffer-related lag and current collapse when the acceptor density in the buffer layer is high. On the other hand, the introduction of backside electrode is effective in reducing drain lag and 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.