Wurtzite AlxGa1−xN bulk crystals grown by molecular beam epitaxy

► We have studied the growth of wurtzite GaN and AlxGa1−xN bulk crystals by molecular beam epitaxy (MBE). ► MBE is normally regarded as an epitaxial technique for the growth of very thin layers with monolayer control of their thickness. However, we have used the MBE technique for bulk crystal growth and have produced wurtzite AlxGa1−xN layers up to 10 μm in thickness. ► We achieved 2 in diameter free-standing bulk wurtzite AlxGa1−xN layers with thicknesses up to ∼10 μm and with Al contents up to 50%. ► The uniform lateral Al distribution in the bulk AlxGa1−xN layers has been confirmed by EPMA and Al depth uniformity has been confirmed by SIMS. ► The fact that free-standing wurtzite AlxGa1−xN wafers can be grown by MBE opens the possibility of the future production of wurtzite AlxGa1−xN substrates optimized for AlGaN-based device structures.