High linearity AlGaN/GaN HEMTs with Au-free Ti/Al/Ni/Ti ohmic contacts for Ka-band applications

Abstract

In this study, AlGaN/GaN HEMTs with Au-free Ti/Al/Ni/Ti ohmic contacts were fabricated. The device presents a contact resistance (Rc) of 0.64 Ω·mm and high linearity characteristics. The two-tone measurement at 28 GHz shows that the 2 × 50 μm device exhibits an excellent third-order intercept point (OIP3) value of 41.64 dBm at VDS = 28 V, and an OIP3/PDC of 24.2. An OIP3 of 46.59 dBm was achieved when the device’s gate width was increased to 8 × 50 μm at VDS = 48 V. These results demonstrate that AlGaN/GaN HEMTs with Ti/Al/Ni/Ti ohmic contacts have potential for Ka-band applications.