Effects of plasma treatment on the Ohmic characteristics of Ti/Al/Ti/Au contacts to n-AlGaN
- GE Global Research Center, Niskayuna, New York 12309 (United States)
The effects of surface treatment using Cl{sub 2}/BCl{sub 3} and Ar inductive coupled plasmas on the Ohmic characteristics of Ti/Al/Ti/Au contacts to n-type Al{sub x}Ga{sub 1-x}N (x=0-0.5) were investigated. Plasma treatment significantly increased the surface conductivity of GaN and Al{sub 0.1}Ga{sub 0.9}N, leading to improved Ohmic behaviors of the contacts. However, it reduced the surface doping level in Al{sub x}Ga{sub 1-x}N (x{>=}0.3) and degraded the contact properties. Following a 900-1000 deg. C anneal, the Ti/Al/Ti/Au contacts to Al{sub x}Ga{sub 1-x}N (x=0-0.3) became truly Ohmic, with specific contact resistances of (3-7)x10{sup -5} {omega} cm{sup 2}, whereas the contact to Al{sub 0.5}Ga{sub 0.5}N remained rectifying even without the plasma treatment. X-ray photoelectron spectroscopy measurements confirmed that the Fermi level moved toward the conduction band in GaN after the plasma treatment, but it was pinned by plasma-induced deep-level states in Al{sub 0.5}Ga{sub 0.5}N. This study emphasizes the need to mitigate plasma damage introduced during the mesa etch step for AlGaN-based deep-UV emitters and detectors.
- OSTI ID:
- 20883181
- Journal Information:
- Applied Physics Letters, Vol. 89, Issue 8; Other Information: DOI: 10.1063/1.2338434; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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