Atomic Layer Deposition of Ga₂O₃ Films from a Dialkylamido-Based Precursor

Abstract

The atomic layer deposition growth of Ga2O3 films was demonstrated using Ga2(NMe2)6 and water with substrate temperatures between 150 and 300 °C. At 250 °C, surface saturative growth was achieved with Ga2(NMe2)6 vapor pulse lengths of ≥1.5 s. The growth rate was 1.0 Å/cycle at substrate temperatures between 170 and 250 °C. Growth rates of 1.1 and 0.89 Å/cycle were observed at 150 and 275 °C, respectively. In a series of films deposited at 250 °C, the film thicknesses varied linearly with the number of deposition cycles. Time-of-flight elastic recoil detection analyses demonstrated stoichiometric Ga2O3 films, with carbon, hydrogen, and nitrogen levels between 1 and 2.1, 4.8−5.4, and 0.6−0.9 at. %, respectively, at substrate temperatures of 170, 200, and 250 °C. The as-deposited films were amorphous, but crystallized to β-Ga2O3 films upon annealing between 700 and 900 °C under a nitrogen atmosphere. Atomic force microscopy showed root-mean-square surface roughnesses of 0.4 and 0.6 nm for films deposited at 170 and 250 °C, respectively.