Effects of plasma treatment on the Ohmic characteristics of Ti/Al/Ti/Au contacts to n-AlGaN

Journal Article · Mon Aug 21 04:00:00 EDT 2006 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.2338434· OSTI ID:20883181

Cao, X A; Piao, H; LeBoeuf, S F; Li, J; Lin, J Y; Jiang, H X ^[1]

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1. 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, Journal Name: Applied Physics Letters Journal Issue: 8 Vol. 89; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM
ALUMINIUM COMPOUNDS
ANNEALING
ARGON
BORON CHLORIDES
CHLORINE
FERMI LEVEL
GALLIUM NITRIDES
GOLD
PLASMA
SURFACE TREATMENTS
TITANIUM
X-RAY PHOTOELECTRON SPECTROSCOPY