CRYSTAL-STRUCTURE AND ORIENTATION OF ALXIN1-XN EPITAXIAL LAYERS GROWN ON (0001)ALPHA-AL2O3 SUBSTRATES

The epitaxial layers of AlxIn1-xN grown on (0001) alpha-Al2O3 substrates by microwave-excited metalorganic vapor phase epitaxy have been studied using the reflection high-energy electron diffraction and X-ray diffraction methods. All AlxIn1-xN layers have a wurtzite structure, as expected from the structure of AlN and InN. The epitaxial relationship between the AlxIn1-xN layers and the (0001) alpha-Al2O3 substrates is found to be (0001)Al(x)In1-xN\\(0001)(alpha-Al2O3) with [1010]AlzIn1-xN\\[10 $$($) over bar 10](alpha-Al2O3). The lattice constants of a and c axes of the epitaxial layers are determined. It is revealed that both the a lattice constant and c/a ratio of the epitaxial Al(x)In1-xN layers decrease with increasing molar fraction of x of the alloy.