Microstructure, electrical properties, and thermal stability of Au-based ohmic contacts to p-GaN
- Materials Research Center, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)
- Center for Solid State Science, Arizona State University, Tempe, Arizona 85287-1704 (United States)
- Argonne National Laboratory, Argonne, Illinois 60439 (United States)
The work described in this paper is part of a systematic study of ohmic contact strategies for GaN-based semiconductors. Au contacts exhibited ohmic behavior on p-GaN when annealed at high temperature. The specific contact resistivity ({rho}{sub c}) calculated from TLM measurements on Au/p-GaN contacts was 53{Omega}{center_dot}cm{sup 2} after annealing at 800{degree}C. Multilayer Au/Mg/Au/p-GaN contacts exhibited linear, ohmic current-voltage (I-V) behavior in the as-deposited condition with {rho}{sub c}=214{Omega}{center_dot}cm{sup 2}. The specific contact resistivity of the multilayer contact increased significantly after rapid thermal annealing (RTA) through 725{degree}C. Cross-sectional microstructural characterization of the Au/p-GaN contact system via high-resolution electron microscopy (HREM) revealed that interfacial secondary phase formation occurred during high-temperature treatments, which coincided with the improvement of contact performance. In the as-deposited multilayer Au/Mg/Au/p-GaN contact, the initial 32 nm Au layer was found to be continuous. However, Mg metal was found in direct contact with the GaN in many places in the sample after annealing at 725{degree}C for 15 s. The resultant increase in contact resistance is believed to be due to the barrier effect increased by the presence of the low work function Mg metal. {copyright} {ital 1997 Materials Research Society.}
- OSTI ID:
- 544821
- Journal Information:
- Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 9 Vol. 12; ISSN JMREEE; ISSN 0884-2914
- Country of Publication:
- United States
- Language:
- English
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