A bilayer Ti/Ag ohmic contact for highly doped n-type GaN films

Abstract

Ohmic contacts with low resistance are fabricated on n-type GaN films using Ti/Ag bilayer metallization. The GaN films are grown by low pressure metalorganic chemical vapor deposition (LP-MOCVD) with Si as the dopant. Ohmic characteristics are studied for films with carrier concentration range from 1.5 x 10(17) to 1.7 x 10(19) cm(-3). The lowest value for the specific contact resistivity of 6.5 x 10(-5) Ohm cm(2) is obtained without annealing. The barrier height of Ti on GaN is calculated to be 0.067 eV. (C) 1996 American Institute of Physics.