Enhancement mode AlGaN/GaN HFET with selectivelygrown <i>pn</i> junction gate

A report is presented into the fabrication and characterisation of an enhancement mode AlGaN/GaN heterojunction field-effect transistor (HFET) with selectively grown pn junction gate. At zero gate bias the device channel is depleted due to the high built-in potential of the gate-channel junction. The selective area growth approach enables both depletion and enhancement mode HFETs to be fabricated on the same wafer thus opening up the possibility of designing high speed, low consumption GaN-based logical integrated circuits.