Growth at GaN/AlN hetero structures: a local view

The local structure at GaN on AlN(0001) heterostructures is studied using p olarization dependent X-ray absorption spectroscopy with synchrotron radiat ion; the Ga K edge has been used and the analysis has been extended up to t he third coordination shell. Samples have been deposited using molecular be am epitaxy with deposition temperatures in the range 620-790 degreesC and a re approximately 6 mn. thick. We find that the GaN/AlN interface is abrupt (no interdiffusion) and that a partially pseudomorphically strained growth occurs, the in-plane strain increasing as the deposition temperature decrea ses. (C) 2001 Elsevier Science B.V. All rights reserved.