Crystal Structure and Orientation of AlxIn 1-xN Epitaxial Layers Grown on (0001) \mbα-Al 2O 3 Substrates

Abstract
The epitaxial layers of AlxIn1-x N grown on (0001) α-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-x N layers have a wurtzite structure, as expected from the structure of AlN and InN. The epitaxial relationship between the AlxIn1-x N layers and the (0001) α-Al2O3 substrates is found to be (0001) Alx In1-x N // (0001)α- Al2 O3 with [101̄0] Alx In1-x N // [101̄0]α- Al2 O3 . 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 AlxIn1-x N layers decrease with increasing molar fraction of x of the alloy.