RF and microwave characteristics of a 10 nm thick InGaN-channel gate recessed HEMT

Abstract

A new depletion-mode gate recessed AlGaN/InGaN/GaN-high electron mobility transistor (HEMT) with 10 nm thickness of InGaN-channel is proposed. A growth of AlGaN over GaN leads to the formation of two-dimensional electron gas (2DEG) at the heterointerface. High 2DEG density (ns) is achieved at the heterointerface due to a strain induced piezoelectric effect between AlGaN and GaN layers. The electrons are confined in the InGaN-channel without spilling over into the buffer layer, which also reduces the buffer leakage current. From the input transfer characteristics the threshold voltage is obtained as −4.5 V and the device conducts a current of 2 A/mm at a drain voltage of 10 V. The device also shows a maximum output current density of 1.8 A/mm at Vds of 3 V. The microwave characteristics like transconductance, cut-off frequency, max frequency of oscillation and Mason's Unilateral Gain of the device are studied by AC small-signal analysis using a two-port network. The stability and power performance of the device are analyzed by the Smith chart and polar plots respectively. To our knowledge this proposed InGaN-channel HEMT structure is the first of its kind.