Substrate-surface orientation dependence of N content in MOVPE growth of GaAsN films on GaAs

The GaAsN films have been grown on GaAs(1 0 0), (1 1 1)A, (1 1 1)B and (0 1 1) substrates at 550 °C by metalorganic vapor-phase epitaxy (MOVPE) to investigate the substrate orientation dependence of the N content. The N content of the GaAsN films estimated from X-ray diffraction (XRD), photoluminescence (PL) and secondary ion mass spectrometry (SIMS) was fairly consistent. At the As/III ratio of 20, the N content is in the order (1 1 1)A>(1 0 0)>(0 1 1)∼(1 1 1)B∼0, which is the same order as that expected from the strain energy arising from the N incorporation. When the tertiarybutylarsine's (TBA's) flow rate is decreased down to the As/III ratio of 5 while the trimethylgallium (TMGa) and 1,1-dimethylhydrazine (DMHy) flow rates are constant, the N content for (1 1 1)B and (0 1 1), as well as (1 0 0) is increased whereas that for (1 1 1)A is almost unchanged, resulting in the order (1 0 0)>(1 1 1)A>(1 1 1)B>(0 1 1). These results may be attributed to the balance between the strain energy and the N desorption efficiency, which will be changed with the coverage of As on the surface.