Organometallic vapor phase epitaxy of GaAs_1-xN_x alloy layers on GaAs(001): Nitrogen incorporation and lattice parameter variation

Epitaxial GaAs_1-xN_x alloy layers, nominally 200-nm-thick, with x up to 0.0375 were grown on GaAs(001) at temperatures T_s varying from 500 to 650 °C to investigate nitrogen incorporation and lattice parameter variations during organometallic vapor phase epitaxy from trimethylgallium, tertiarybutylarsine, and 1,1-dimethylhydrazine. Quantitative secondary ion mass spectrometry measurements (SIMS) indicate that N incorporation decreases systematically with increasing T_s to become almost negligible at 650 °C. All films are coherent with the substrate as judged by high-resolution x-ray reciprocal lattice mapping although atomic force microscopy and cross-sectional transmission electron microscopy reveal the presence of cracks in films with x≫0.02. High-resolution x-ray diffraction measurements combined with SIMS analyses indicate that the lattice constant decreases linearly with increasing x following closely the predictions of Vegard’s rule for x≪0.03. At higher concentrations, the lattice constant decreases more rapidly as a significant fraction of N atoms becomes incorporated in nonsubstitutional sites as demonstrated by nuclear reaction analysis. © 2004 American Vacuum Society.