Low energy ion beam assisted deposition (IBAD) of refractory tungsten nitride films onto GaAs is attempted for the first time. This ion beam technique provides lower process pressure, and less ion damage to substrates and films than conventional reactive sputter deposition. Schottky diode characteristics of W/ and WNx/GaAs and their thermal stability were investigated by capping the refractory films with SiO2films and subsequent annealing at 700–900 °C for 30 min. While both tungsten and tungsten nitride contacts were stable up to 850 °C, the tungsten nitride contact showed better thermal stability and higher Schottky barrier height. The Schottky barrier heights of W/ and WN0.27/GaAs diodes annealed at 850 °C were 0.71 and 0.84 eV, respectively. These preliminary results are comparable to those of the best results reported with the conventional sputtering methods.