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Proceedings Paper

Ohmic contacts to n-GaN formed by ion-implanted Si into p-GaN
Author(s): Xichang Bao; Jintong Xu; Wenjing Zhang; Ling Wang; Kaihui Chu; Chao Li; Xiangyang Li
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Paper Abstract

In this paper, we report the ohmic contact to n-GaN fabricated by implanting silicon into Mg-doped GaN using an alloy of Ti/Al/Ti/Au metallization. The used materials were grown on (001) sapphire substrates by metal-organic chemical-vapor deposition (MOCVD). The layer structure was comprised of a GaN buffer layer and followed by a 2 μm thickness Mg-doped GaN (Na=5×1017cm-3) and then double silicon implantation was performed in order to convert p-type GaN into n-type GaN films. The as-implanted samples were then thermal annealed at 1150 °C for 5 min in N2 ambient. The carrier concentration and Hall mobility were 3.13×1018 cm3 and 112 cm2/ (V·s) measured by Hall method. Multilayer electrode of Ti (50 nm)/Al (50 nm)/Ti (30 nm)/Au (30 nm) was deposited on n-GaN using an electron-beam evaporation and contacts were formed by a N2 annealing technique ranging from 600 to 900 °C. After annealing lower than 700 °C, the contacts exhibited a rectifying behavior and became ohmic contact only after high temperature processes (≥700 °C). Specific contact resistance was as low as 9.58×10-4 Ω·cm2 after annealing at 800 °C for 60 seconds. While annealing temperature is higher than 800 °C, the specific contact resistance becomes worse. This phenomenon is caused by the surface morphology degradation.

Paper Details

Date Published: 24 August 2009
PDF: 6 pages
Proc. SPIE 7381, International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, 73810V (24 August 2009); doi: 10.1117/12.835500
Show Author Affiliations
Xichang Bao, Shanghai Institute of Technical Physics (China)
Jintong Xu, Shanghai Institute of Technical Physics (China)
Wenjing Zhang, Shanghai Institute of Technical Physics (China)
Ling Wang, Shanghai Institute of Technical Physics (China)
Kaihui Chu, Shanghai Institute of Technical Physics (China)
Chao Li, Shanghai Institute of Technical Physics (China)
Xiangyang Li, Shanghai Institute of Technical Physics (China)


Published in SPIE Proceedings Vol. 7381:
International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors
Xu-yuan Chen; Yue-lin Wang; Zhi-ping Zhou; Qing-kang Wang, Editor(s)

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