Reduction in Lags and Current Collapse in Field-Plate AlGaN/GaN HEMTs with High Acceptor Density in a Buffer Layer

摘要

We make a two-dimensional transient analysis of field-plate AlGaN/GaN HEMTs with a semi-insulating buffer layer, where a deep acceptor above the midgap is considered. It is studied how the deep-acceptor density NDA and the field plate affect buffer-related lag phenomena and current collapse. NDA is varied between 1017 cm~(-3) and 8x10~(17) cm~(-3). It is shown that without a field plate the drain lag and current collapse increase with increasing N_(DA) as expected, although the gate lag decreases when N_(DA) becomes higher than 2x10~(17) cm~(-3). But with a field plate, surprisingly, the lags and current collapse decrease when N_(DA) becomes high. This is attributed to the fact that the reduction in drain lag and current collapse by introducing a field plate becomes more significant when N_(DA) becomes higher.