Zinc-blende and wurtzite Al_x)Gai_(1_x)N bulk crystals grown by molecular beam epitaxy

摘要

There is a significant difference in the lattice parameters of GaN and A1N and for many device applications Al_xGa_(1-x)N substrates would be preferable to either GaN or A1N. We have studied the growth of free-standing zinc-blende and wurtzite Al_xGa_(1-x)N bulk crystals by plasma-assisted molecular beam epitaxy (PA-MBE). Thick (～10 μm) zinc-blende and wurtzite Al_x)Ga_(1-x)N films were grown by PA-MBE on 2-in. GaAs (0 01) and GaAs (1 1 1)B substrates respectively and were removed from the GaAs substrate after the growth. We demonstrate that free-standing zinc-blende and wurtzite Al_xGa_(1-x),N wafers can be achieved by PA-MBE for a wide range of Al compositions.