Scaling behavior of InAlN/GaN HEMTs on silicon for RF applications

Due to the low cost and the scaling capability of Si substrate, InAlN/GaN high-electron-mobility transistors (HEMTs) on silicon substrate have attracted more and more attentions. In this paper, a high-performance 50-nm-gate-length InAlN/GaN HEMT on Si with a high on/off current (I(on)/I(off)) ratio of 7.28 × 10(6), an average subthreshold swing (SS) of 72 mV/dec, a low drain-induced barrier lowing (DIBL) of 88 mV, an off-state three-terminal breakdown voltage (BV(ds)) of 36 V, a current/power gain cutoff frequency (f(T)/f(max)) of 140/215 GHz, and a Johnson’s figure-of-merit (JFOM) of 5.04 THz V is simultaneously demonstrated. The device extrinsic and intrinsic parameters are extracted using equivalent circuit model, which is verified by the good agreement between simulated and measured S-parameter values. Then the scaling behavior of InAlN/GaN HEMTs on Si is predicted using the extracted extrinsic and intrinsic parameters of devices with different gate lengths (L(g)). It presents that a f(T)/f(max) of 230/327 GHz can be achieved when L(g) scales down to 20 nm with the technology developed in the study, and an improved f(T)/f(max) of 320/535 GHz can be achieved on a 20-nm-gate-length InAlN/GaN HEMT with regrown ohmic contact technology and 30% decreased parasitic capacitance. This study confirms the feasibility of further improvement of InAlN/GaN HEMTs on Si for RF applications.