Carrier transport mechanism of a low resistance Ti/Al ohmic contact on (1122) semipolar n-Type GaN

The carrier transport mechanism of a low resistance Ti/Al Ohmic contact to (1122) semipolar n-type GaN grown on m-plane sapphire substrate was investigated. Thermal annealing led to an excellent Ohmic contact with a specific contact resistance of 3.2 × 10 ^-4 Ω cm ². Current-voltage-temperature measurements revealed insignificant changes in the specific contact resistance with respect to temperature, which is evidence of a tunneling transport. Based on the thermionic field emission model, a very low Schottky barrier height of 3meV and barrier width of 1 nm were obtained due to increased interfacial carriers of 9.2 × 10 ¹⁸ cm ^-3, resulting in excellent Ohmic contact to semipolar n-type GaN.