Microstructural characterization of radio frequency magnetron sputter-deposited Ga2O3:Mn phosphor thin films

Ga 2 O 3 : Mn phosphor thin films have been prepared by radio frequency (rf) magnetron sputtering of a 2 mol % Mn-doped Ga2O3 target in an oxygen–argon mixture atmosphere. The deposition rate of the films decreased from 14 to 12 Å/min when the working gas pressure decreased from 30 to 2 mTorr, while the O/Ga ratio of ∼1.5 did not systematically depend on the pressure. Films deposited at higher working gas pressure had a porous columnar structure containing a large void, typical of zone 1 growth, while films produced at lower pressure had relatively smooth surfaces with a dense structure, typical of zone T growth. The results obtained are consistent with energetic particle bombardment of the depositing films promoting surface adatom mobility at lower working gas pressure. Films deposited at working gas pressures⩾15 mTorr showed a random orientation after a postdeposition anneal at 1000 °C. Below 15 mTorr, annealed films were strongly textured with the (111) and (020) planes parallel to the surface.