Low Specific On-Resistance AlGaN/AlN/GaN High Electron Mobility Transistors on High Resistivity Silicon Substrate

High performance undoped AlGaN/AlN/GaN high electron mobility transistors (HEMTs) on high resistivity Si were achieved by implementing an ohmic-recess contact by inductively coupled plasma etching using four layers of Ti/Al/Ni/Au metal. About a 17.5% increase in drain current density and a 12.5% increase in extrinsic transconductance were observed on ohmic-recess-etched HEMTs. This is due to the reduction in the parasitic resistance such as contact resistance, drain resistance, and source resistance of the device. The ohmic-recess-etched AlGaN/AlN/GaN HEMT with a 6.0 mu m gate-drain spacing exhibited the lowest specific on-resistance (R(DS(ON)) of 0.22 m Omega cm(2) with an off-state breakdown voltage (BV(GD)) of 194 V. The highest ever reported figure-of-merit BV(GD)(2)/R(DS(ON)) = 1.79 x 10(8) V(2) Omega(-1) cm(-2) has been achieved in the ohmic-recess-etched AlGaN/AlN/GaN HEMTs on silicon. Ohmic recess is useful for undoped AlGaN/AlN/GaN HEMTs to achieve low R(DS(ON)) with high figure-of-merit. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3339068] All rights reserved.