Thermal stability of α-(AlxGa1-x)2O3 films grown on c-plane sapphire substrates with an Al composition up to 90%

The thermal stability of alpha-(AlxGa1-x)(2)O-3 films grown on c-plane sapphire substrates was investigated. The alpha-(AlxGa1-x)(2)O-3 epitaxial films grown by mist chemical vapor deposition were annealed at temperatures in the range of 600 degrees C-1100 degrees C in an atmospheric furnace, and then the crystal structures of the films were characterized using X-ray diffraction and transmission electron microscopy. When the Al composition was less than 0.5, the alpha-(AlxGa1-x)(2)O-3 films converted to the beta-phase, which is the thermodynamically most stable phase for Ga2O3. The thermal stability was enhanced by increase in the Al composition, and alpha-(AlxGa1-x)(2)O-3 with x = 0.45 maintained the corundum structure after annealing at 950 degrees C. On the other hand, the alpha-(AlxGa1-x)(2)O-3 layers with Al contents higher than 0.6 were stable against the thermal treatment and did not show phase transformation to other phases upon high-temperature annealing at 1100 degrees C.

Automated summary

The thermal stability of alpha-(AlxGa1-x)(2)O-3 films grown on c-plane sapphire substrates was explored through annealing at different temperatures. It was found that lower Al composition led to phase transformation to the most stable phase for Ga2O3, while higher Al composition improved thermal stability. Films with x = 0.45 maintained the corundum structure after annealing at 950 degrees C, while layers with Al contents above 0.6 remained stable and did not undergo phase transformation at 1100 degrees C.