Selective sublimation of GaN and regrowth of AlGaN to co-integrate enhancement mode and depletion mode high electron mobility transistors.

• Selective sublimation of p-GaN is developed to fabricate enhancement-mode HEMTs. • AlGaN regrowth drastically reduces access resistances in enhancement-mode HEMTs. • Sublimation and regrowth are combined to co-integrate E/D-mode GaN HEMTs. In the present study, the selective sublimation of the p-GaN cap layer of Al(Ga)N/GaN HEMTs is developed to replace the commonly used dry etching with no risk of damage in the barrier layer in order to fabricate enhanced mode transistors. Thanks to this approach, enhancement-mode transistors are fabricated with a threshold voltage between 0 V and +1.5 V depending on the barrier layer aluminum molar fraction and thickness. Furthermore, we show the benefit of the combination of selective sublimation with the regrowth of AlGaN to reduce access resistance in these transistors which can be co-integrated with depletion-mode devices fabricated in the same process in areas where p-GaN has been totally evaporated. [ABSTRACT FROM AUTHOR]