Low-resistance ohmic contacts to p-type GaN
- 8 May 2000
- journal article
- research article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 76 (19) , 2728-2730
- https://doi.org/10.1063/1.126457
Abstract
The specific contact resistance of two types of ohmic contacts to p-type GaN is analyzed. First, an ohmic contact formed by a metalelectrodedeposited on a highly dopedp-type GaN layer. Second, an ohmic contact formed by a metalelectrodedeposited on a thin GaN layer with an internal electric field caused by polarization effects. It is shown that contacts mediated by polarization effects can result, for typical materials parameters, in low contact resistances comparable or better than contacts mediated by dopant-inducedsurface fields. A type of contact is proposed and demonstrated. These contacts employ polarization charges to enhance tunneling transport as well as high doping. Experimental results on Ni contacts to p-type Al x Ga 1−x N/GaN doped superlattices are presented. The contacts have linear current–voltage characteristics with contact resistances of 9.3×10 −4 Ω cm 2 , as inferred from linear transmission-line method measurements. The influence of annealing at temperatures ranging from 400 to 500 °C on the contact resistance is studied.Keywords
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