Low temperature deposition of Ga2O3 thin films using trimethylgallium and oxygen plasma

Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced atomic layer deposition (ALD) using trimethylgallium as the gallium precursor and oxygen plasma as the oxidant. A wide ALD temperature window was observed from 100 to 400 degrees C, where deposition rate was constant at similar to 0.53 angstrom/cycle. X-ray photoelectron spectroscopy survey scans indicated the presence of gallium, oxygen, and carbon elements with concentrations of similar to 36, similar to 51.8, and similar to 12.2 at. %, respectively. As-deposited films were amorphous; upon annealing at 900 degrees C under N-2 atmosphere for 30 min, polycrystalline beta-Ga2O3 phase with a monoclinic crystal structure was obtained. Refractive index and root mean square roughness of the annealed Ga2O3 film were higher than those of the as-deposited due to crystallization. (C) 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4758782]