MBE growth of cubic AlN films on MgO substrate via cubic GaN buffer layer

The effect of a cubic GaN (c-GaN) buffer layer in the cubic AlN (c-AlN) growth on MgO substrate was investigated. Cubic AlN films were grown on MgO(001) substrates via a c-GaN buffer layer by RF-MBE. The c-AlN growth was confirmed by RHEED and XRD reciprocal space mapping analysis. On the other hand, no cubic AlN was grown without the c-GaN buffer. Therefore the cGaN buffer is necessary for the growth of c-AlN on MgO. It is considered that the lesser lattice-mismatch between c-AlN and c-GaN than c-AlN and MgO suppresses the hexagonal-phase inclusion. Only 0.5-nm-thick c-GaN buffer layer is enough for the c-AlN growth although the thin buffer layer causes rough surfaces of the c-AlN films. The effect of the c-AlN film growth condition on the c-AlN structural properties was also investigated. The growth temperature of 700 C and an Al-rich growing surface are required for the growth of smooth-surface c-AlN films. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim