Study of GaN Thick Films Grown on Different Nitridated Ga2O3 Films

In this paper, various Ga2O3 films, including amorphous Ga2O3 films, β-Ga2O3, and α-Ga2O3 epitaxial films, have been nitridated and converted to single-crystalline GaN layers on the surface. Although the original Ga2O3 films are different, all the converted GaN layers exhibit the (002) preferred orientation and the porous morphologies. The ~200 µm GaN thick films have been grown on the nitridated Ga2O3 films using the halide vapor phase epitaxy (HVPE) method. Raman analysis indicates that all the HVPE-GaN films grown on nitridated Ga2O3 films are almost stress-free. An obvious GaN porous layer/Ga2O3 structure has been observed in the interface between GaN thick films and sapphire substrates. The porous GaN layers can be used as promising templates for the preparation of free-standing GaN substrates.