p-Channel Enhancement and Depletion Mode GaN-Based HFETs With Quaternary Backbarriers

Within the last years, III-nitride-based devices have been demonstrated with exceptional performance. There is, however, a severe lack of knowledge when it comes fabrication of p-channel devices. p-Channel heterostructure field-effect transistors (HFETs) could open the way for nitride-based complementary logic. Here, a comprehensive study of enhancement and depletion mode p-channel GaN/AlInGaN HFETs is performed. The influence of a highly p-doped GaN cap layer on device performance is investigated. Gate recessing and changes in composition of the backbarrier are analyzed. ON/OFF ratios of up to 10
⁸
and subthreshold swings of about 75 mV/decade are achieved.