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Title: Microstructure of V-based ohmic contacts to AlGaN/GaN heterostructures at a reduced annealing temperature

Ohmic contacts with V/Al/Ni/Au and V/Ni/Au metalization schemes were deposited on AlGaN/GaN heterostructures. The dependence of the specific contact resistance on the annealing conditions and the V:Al thickness ratio was shown. For an optimized electrode stack, a low specific contact resistance of 8.9 × 10{sup −6} Ω cm{sup 2} was achieved at an annealing temperature of 650 °C. Compared to the conventional Ti/Al/Ni/Au contact, this is a reduction of 150 K. The microstructure and contact formation at the AlGaN/metal interface were investigated by transmission electron microscopy including high-resolution micrographs and energy dispersive X-ray analysis. It was shown that for low-resistive contacts, the resistivity of the metalization has to be taken into account. The V:Al thickness ratio has an impact on the formation of different intermetallic phases and thus is crucial for establishing ohmic contacts at reduced annealing temperatures.
Authors:
; ; ;  [1] ;  [2] ; ;  [3]
  1. Institute of Applied Physics, TU Bergakademie Freiberg, 09599 Freiberg (Germany)
  2. Namlab gGmbH, 01187 Dresden (Germany)
  3. Institute of Materials Science, TU Bergakademie Freiberg, 09599 Freiberg (Germany)
Publication Date:
OSTI Identifier:
22420280
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM; ALUMINIUM COMPOUNDS; ANNEALING; DEPOSITS; ELECTRIC CONDUCTIVITY; ELECTRIC CONTACTS; GALLIUM NITRIDES; GOLD; MICROSTRUCTURE; NICKEL; TRANSMISSION ELECTRON MICROSCOPY; VANADIUM; X RADIATION