RF Performance of InAlN/GaN HFETs and MOSHFETs With fT × LG up to 21 GHz·

The RF performance of lattice-matched InAlN/GaN heterostructure field-effect transistors (HFETs) andAl₂O₃/InAlN/GaN metal–oxide–semiconductor HFETs (MOSHFETs) with varied gate length was evaluated. The current gain cutoff frequencyfTand the maximum oscillation frequencyfₘₐₓfor the HFETs with 0.3-gate length were 54 and 58 GHz, respectively. An increase offTto 61 GHz and offₘₐₓto 70 GHz was obtained for the MOSHFETs. The HFETs and MOSHFETs with different gate length yielded anfT × LGproduct of 18 and 21GHz·, respectively. These are higher values than reported yet on InAlN/GaN devices and similar to those known for AlGaN/GaN HFETs.