ION-BEAM ASSISTED DEPOSITION OF TUNGSTEN ON GAAS

Ion beam assisted deposition of W on GaAs has been performed by irradiating low energy (500–2000 eV) H2+or Ar+beams in WF6ambient. The low energy beams were used to reduce damage in the substrate. The damage and annealing properties were examined by Schottky barrier characteristics and the DLTS method. W films with purity better than 90% and resistivity of ∼10-5Ω·cm were deposited. Schottky contacts were formed by 500 eV H2+and all Ar+irradiation without any annealing, though the leakage current was larger for Ar+irradiation, while almost ohmic contacts were formed for 2000 eV beam irradiation, probably due to the thicker damaged layer in the substrates. Annealing at 350°C for 10 min yielded decreased reverse leakage current by more than two orders of magnitude and good Schottky contacts with n-factor ∼1. © 1990 IOP Publishing Ltd.