Extending the bounds of performance in E-mode p-channel GaN MOSHFETs

An investigation of the distribution of the electric field within a normally-off p-channel heterostructure field-effect transistor in GaN, explains why a high |V
_th
| requires a reduction of the thickness of oxide and the GaN channel layer. The trade-off between on-current |I
_on
| and |V
_th
|, responsible for the poor |I
_ON
| in E-mode devices is overcome with an additional cap AlGaN layer that modulates the electric field in itself and the oxide. A record |I
_on
| of 50-60 mA/mm is achieved with a |V
_th
| greater than |-2| V in the designed E-mode p-channel MOSHFET, which is more than double that in a conventional device.