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Title: Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.
Authors:
; ; ; ;  [1] ;  [2] ; ;  [3]
  1. Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China)
  2. School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)
  3. Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)
Publication Date:
OSTI Identifier:
22412850
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 2; 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; AGGLOMERATION; ALUMINIUM; ANNEALING; AUGER ELECTRON SPECTROSCOPY; ELECTRIC CONDUCTIVITY; FIELD EMISSION; INTERFACES; MORPHOLOGY; NICKEL; OXIDATION; PHASE STABILITY; ROUGHNESS; SILICON CARBIDES; SURFACES; TEMPERATURE DEPENDENCE; TITANIUM; TITANIUM CARBIDES; X-RAY SPECTRA