Thermal annealing behaviour of Al/Ni/Au multilayer on n-GaN Schottky contacts
Liu Fang(刘芳)a), Wang Tao(王涛)a), Shen Bo(沈波)b), Huang Sen(黄森)b), Lin Fang(林芳)b), Ma Nan(马楠)b), Xu Fu-Jun(许福军)b), Wang Peng(王鹏)a), and Yao Jian-Quan(姚建铨)a)
a College of Precision Instrument and Opto-Electronics Engineering, Institute of Laser and Optoelectronics, Tianjin University, Key Laboratory of Optoelectric Information Science and Technology of Ministry of Education, Tianjin University, Tianjin 300072, China; b State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Abstract Recently GaN-based high electron mobility transistors (HEMTs) have revealed the superior properties of a high breakdown field and high electron saturation velocity. Reduction of the gate leakage current is one of the key issues to be solved for their further improvement. This paper reports that an Al layer as thin as 3 nm was inserted between the conventional Ni/Au Schottky contact and n-GaN epilayers, and the Schottky behaviour of Al/Ni/Au contact was investigated under various annealing conditions by current--voltage (I--V) measurements. A non-linear fitting method was used to extract the contact parameters from the I--V characteristic curves. Experimental results indicate that reduction of the gate leakage current by as much as four orders of magnitude was successfully recorded by thermal annealing. And high quality Schottky contact with a barrier height of 0.875 eV and the lowest reverse-bias leakage current, respectively, can be obtained under 12 min annealing at 450°C in N2 ambience.
Received: 15 September 2008
Revised: 07 November 2008
Accepted manuscript online:
PACS:
73.30.+y
(Surface double layers, Schottky barriers, and work functions)
(Semiconductor-device characterization, design, and modeling)
Cite this article:
Liu Fang(刘芳), Wang Tao(王涛), Shen Bo(沈波), Huang Sen(黄森), Lin Fang(林芳), Ma Nan(马楠), Xu Fu-Jun(许福军), Wang Peng(王鹏), and Yao Jian-Quan(姚建铨) Thermal annealing behaviour of Al/Ni/Au multilayer on n-GaN Schottky contacts 2009 Chin. Phys. B 18 1618
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