Room-temperature Ohmic contact on n-type GaN with surface treatment using Cl2 inductively coupled plasma

A room-temperature Ti/Al Ohmic contact on n-type GaN was obtained by surface treatment using Cl-2 inductively coupled plasma treatment. The specific contact resistivity was dramatically decreased from the Schottky behavior to 9.4x10(-6) Omega cm(2) by the treatment. The binding energy of the Ga-N bond and the atomic ratio of Ga/N were simultaneously increased after the plasma treatment. This provides evidence that N vacancies, acting as donors for electrons, were produced at the etched surface, resulting in a shift of the Fermi level near to the conduction band. This leads to the reduction in contact resistivity through the decrease of the Schottky barrier for the conduction of electrons. (C) 2001 American Institute of Physics.