InxAl1-xN/AlN/GaN High Electron Mobility Transistor Structures on 200 mm Diameter Si(111) Substrates with Au-Free Device Processing

Abstract

InxAl1-xN/AlN/GaN-based high electron mobility transistor (HEMT) structures are epitaxially grown on 200 mm diameter Si(111) substrates by a metal organic chemical vapor deposition technique. The structural and electrical properties of the nitride layers are addressed by high-resolution X-ray diffraction and Hall effect measurements. The fabricated HEMTs with Au-free contact metallization schemes have resulted in an ON-OFF current ratio ∼105. Ti/Al/Ni/W-based Ohmic source/drain contacts, with 1.5 μm RuOx Schottky gate on In0.15Al0.85N/AlN/GaN HEMTs at VDS = 10 V, show a maximum transconductance (gm) and saturation drain current (IDSAT) of 0.19 ± 0.01 S/mm and 0.82 ± 0.02 A/mm, respectively, with a reasonable uniformity from the center to edge of a 200 mm diameter epiwafer.