Low-Resistance Ti/Au Ohmic Contact on (001) Plane Ga <sub>2</sub> O <sub>3</sub> Crystal
Yu‐Kyung Kim, Man-Kyung Kim, Kwang Hyeon Baik, Soohwan Jang
Abstract
We studied the Ti/Au Ohmic contact on (001) plane Ga 2 O 3 single crystal wafer as a function of annealing temperature and crystallographic orientation. The lowest specific contact resistances of ∼5 × 10 −4 Ω·cm 2 were obtained at 400 °C annealing temperature under nitrogen ambience. The Ohmic metal contact became degraded when annealed above 500 °C. The formation of Ti oxide might be responsible for the degradation of Ohmic contact at high annealing temperatures. In comparison with (010) Ga 2 O 3 substrate, the Ohmic contact could be more easily formed on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mover accent="true"> <mml:mn>2</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> <mml:mn>01</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> and (001) Ga 2 O 3 planes, possibly due to high surface energy and dangling bond density. It is notable that the contact properties did not show any particular dependence on in-plane azimuth angles on (001) Ga 2 O 3 substrate.