Field-Effect Transistors with High Electron Mobility on an AlGaN/GaN Heterostructure with Gate Recessing into the Barrier Layer

Abstract—The influence of the thickness of the barrier layer of a nitride heterostructure on the characteristics of field-effect transistors with high electron mobility (high electron mobility transistors, HEMTs) is considered. Reducing the thickness of the barrier layer will increase the transconductance of the transistor, its operating frequencies, gain, and specific output power. This paper considers the change in the thickness of the barrier layer of the heterostructure due to gate recession. The developed and implemented method of low-energy defect-free dry etching of the AlGaN barrier layer is used, which consists in the cyclic repetition of operations of the plasma-chemical oxidation of AlGaN and removal of the formed oxide layer by reactive-ion etching in inductively coupled plasma in a chlorine-containing medium. For the first time, AlGaN/AlN/GaN HEMTs with a gate recess are fabricated using the proposed etching method. In this case, the current values of the obtained transistors do not depend on the number of etching cycles, the position of the operating point along the gate is shifted towards positive voltages (up to transistors operating in the enrichment mode).