Thermal stability of β-Ga2O3 in mixed flows of H2 and N2

The thermal stability of beta-Ga2O3(010) substrates was investigated at atmospheric pressure between 250 and 1450 degrees C in a flow of either N-2 or a mixture of H-2 and N-2 using a radio-frequency induction furnace. The beta-Ga2O3 surface was found to decompose at and above 1150 degrees C in N-2, while the decomposition of beta-Ga2O3 began at only 350 degrees C in the presence of H-2. Heating beta-Ga2O3 substrates in gas flows containing different molar fractions of H-2 demonstrated that the decomposition was promoted by increasing the H-2 molar fractions. Thermodynamic analysis showed that the dominant reactions are Ga2O3(s) = Ga2O(g) + O-2(g) in N-2 and Ga2O3(s) + 2H(2)(g) = Ga2O(g) = 2H(2)O(g) in a mixed flow of H-2 and N-2. The second-order reaction with respect to H-2 determined for the mixed flows agrees with the experimental results for the dependence of the beta-Ga2O3 decomposition rates on the H-2 molar fraction. (c) 2015 The Japan Society of Applied Physics