Rutherford backscattering/channeling study of a thin AlGaN layer on Al(2)O(0)3(0001).

Abstract A thin AlGaN layer, which is suitable for structural study using Rutherford backscattering (RBS)/channeling, was grown on an Al 2 O 3 (0 0 0 1) substrate by metalorganic chemical vapor deposition. The results show that the composition of the epilayer is Al 0.05 Ga 0.95 N and that although the epilayer is very thin (79 nm), it has a good crystalline quality ( χ min =1.9%). The azimuthal orientation of the AlGaN epilayer relative to the Al 2 O 3 substrate is AlGaN[0 0 0 1] // Al 2 O 3 [0 0 0 1] and AlGaN {1 1 2 0} // Al 2 O 3 {1 0 1 0} , showing that the AlGaN epilayer is rotated by 30° around the [0 0 0 1] axis with respect to the Al 2 O 3 substrate which decreases the lattice mismatch between the epilayer and the substrate significantly. RBS angular scan was used to determine the strain-induced tetragonal distortion of the epilayer. Combined with X-ray diffraction, the perpendicular and parallel elastic strains of the AlGaN layer, e ⊥ =+0.31% and e ∥ =−0.28%, can be calculated.