Ion beam characterization of GaAs1-x-yNxBiy epitaxial layers

Incorporation of Bi in GaAs1-xNx epitaxial layers represents a significant interest as Bi compensates the lattice parameter reduction caused by the N incorporation while contributing to the reduction of the band gap energy. GaAs1-x-yNxBiy epitaxial layers were grown on GaAs wafers by molecular beam epitaxy. The quality of the films as well as the concentration and lattice location of Bi and N were characterized by channeling Rutherford backscattering spectrometry and nuclear reaction analysis using 2 and 3.72 MeV He beams, respectively. The amount of nitrogen in the film was measured by means of the 14N(α, p)17O endothermic nuclear reaction and elastic recoil detection. The results indicate that high quality epitaxial layers were obtained, with y=1.8% Bi incorporated into the layer. Angular scan along the main axes showed no strain in the film and indicated that most of Bi atoms are located at substitutional sites. Nitrogen lattice incorporation is more difficult to establish because of the presence of Bi in the layer, but we estimate the substitutional fraction to be 71 ± 6%