Ohmic contacts to n-GaN formed by ion-implanted Si into p-GaN

Xichang Bao; Jintong Xu; Wenjing Zhang; Ling Wang; Kaihui Chu; Chao Li; Xiangyang Li

doi:10.1117/12.835500

24 August 2009 Ohmic contacts to n-GaN formed by ion-implanted Si into p-GaN

Xichang Bao, Jintong Xu, Wenjing Zhang, Ling Wang, Kaihui Chu, Chao Li, Xiangyang Li

Proceedings Volume 7381, International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors; 73810V (2009) https://doi.org/10.1117/12.835500
Event: International Symposium on Photoelectronic Detection and Imaging 2009, 2009, Beijing, China

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 (N_a=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.

Citation Download Citation

Xichang Bao, Jintong Xu, Wenjing Zhang, Ling Wang, Kaihui Chu, Chao Li, and Xiangyang Li "Ohmic contacts to n-GaN formed by ion-implanted Si into p-GaN", Proc. SPIE 7381, International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, 73810V (24 August 2009); https://doi.org/10.1117/12.835500

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