Positron beam measurements were performed on 7 thin film AlN layers on silicon grown by metal-organic vapour phase epitaxy under various conditions. The growth temperature, V/III supply ratio of the precursor molecules and the layer thicknesses were varied. All the samples grown had a high concentration of vacancy type defects; suggesting that structural defects and possible strain due to lattice mismatch played major roles in vacancy formation. Also, the growth conditions had an effect upon the vacancy content. Increasing growth temperatures and decreasing layer thickness seemed to increase the vacancy concentration whereas the V/III ratio of the growth gases did not seem to have any effect

Effect of Growth Conditions on Vacancy Defects in MOVPE Grown AlN Thin Layers. J.M.Mäki, F.Tuomisto, B.Bastek, F.Bertam, J.Christen, A.Dadgar, A.Krost: Physica Status Solidi C, 2009, 6[11], 2575-7