Ohmic contacts with low resistance and low barrier height were fabricated on n-type GaN films using W metallization. The n-type GaN films were grown by low pressure metalorganic chemical vapor deposition (LPMOCVD) with Si as the dopant. Ohmic characteristics were studied for GaN films with Si carrier concentration varying from 1.4 x 10(17) to 1.8 x 10(19) cm(-3). The specific contact resistivity were reduced with increasing Si-doping concentration on as-deposited W/GaN films, and the lowest value was 3.6 x 10(-4) Ohm cm(2) on n-type GaN with a concentration of 1.8 x 10(19) cm(-3). After rapid thermal annealing (RTA) treatment on W/GaN films at 1000 degrees C for 30 s, the specific contact resistivity were reduced to 1 x 10(-4) Ohm cm(2). The W metal on n-type GaN films, show that good thermal stability varied the annealing temperatures. The barrier height of as-deposited W metal on GaN is calculated to be 0.058 eV.