Low resistance Pd/Au ohmic contacts to p-type GaN using surface treatment

Ohmic contact to p-type GaN with the lowest contact resistivity was developed by the surface treatment prior to Pd/Au metal deposition. The contact resistivity drastically decreased from 2.9 x 10(-2) to 4.3 x 10(-4) Ohm cm(2) by the surface treatment using aqua regia. The surface treatment plays a role in removing the surface oxide formed on p-type GaN during epitaxial growth, and subsequently in reducing the barrier height for holes at the interface of Pd/ p-type GaN, resulting in the good ohmic contacts to p-type GaN. (C) 1998 American Institute of Physics. [S0003-6951(98)01246-7].