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Effect of Au distribution in NiO/Au film on the ohmic contact formation to p-type GaN

Published online by Cambridge University Press:  03 March 2011

Jiin-Long Yang ,
J.S. Chen  and
S.J. Chang
Jiin-Long Yang
Affiliation:
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China
J.S. Chen*
Affiliation:
Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China
S.J. Chang
Affiliation:
Department of Electrical Engineering, Institute of Microelectronics, National Cheng Kung University, Tainan 70101, Taiwan, Republic of China
*
a) Address all correspondence to this author. e-mail: jenschen@mail.ncku.edu.tw
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Abstract

The distribution of Au and NiO in NiO/Au ohmic contact on p-type GaN was investigated in this work. Au (5 nm) films were deposited on p-GaN substrates by magnetron sputtering. Some of the Au films were preheated in N2 ambient to agglomerate into semi-connected structure (abbreviated by agg-Au); others were not preheated and remained the continuous (abbreviated by cont-Au). A NiO film (5 nm) was deposited on both types of samples, and all samples were subsequently annealed in N2 ambient at the temperatures ranging from 100 to 500 °C. The surface morphology, phases, and cross-sectional microstructure were investigated by scanning electron microscopy, glancing incident angle x-ray diffraction, and transmission electron microscopy. I-V measurement on the contacts indicates that only the 400 °C annealed NiO/cont-Au/p-GaN sample exhibits ohmic behavior and its specific contact resistance (ρc) is 8.93 × 10−3 Ω cm2. After annealing, Au and NiO contact to GaN individually in the NiO/agg-Au/p-GaN system while the Au and NiO layers become tangled in the NiO/cont-Au/p-GaN system. As a result, the highly tangled NiO-Au structure shall be the key to achieve the ohmic behavior for NiO/cont-Au/p-GaN system.

Keywords

Electrical propertiesMicrostructureSputtering
Type
Articles
Information
Journal of Materials Research , Volume 20 , Issue 2 , February 2005 , pp. 456 - 463
Copyright
Copyright © Materials Research Society 2005

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