The effect of the AlxGa1−xN/AIN buffer layer on the properties of GaN/Si(1 1 1) film grown by NH3-MBE

We describe the growth of GaN on Si(1 1 1) substrates with AlxGa1−xN/AlN buffer layer by ammonia gas source molecular beam epitaxy (NH3-GSMBE). The influence of the AlN and AlxGa1−xN buffer layer thickness and the Al composition on the crack density of GaN has been investigated. It is found that the optimum thickness is 120 and 250 nm for AlN and AlxGa1−xN layers, respectively. The optimum Al composition is between 0.3