X-ray absorption fine-structure techniques have been utilized to probe the short-range structures around N and In in ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}{\mathrm{As}}_{1-y}{\mathrm{N}}_y$ compounds containing about 3% of N and 8% of In. Our results indicate that N impurities most likely substitute for As atoms in the system. The In-As interatomic distance in these compounds remains practically the same as in InAs, while the coordination number of As atoms around In shows possible variations with changes in the material characteristics. The N atoms play an important role in affecting the changes of band gap while also serving as “strain moderators” by providing a tensile strain in the film to counteract the compressive strain caused by the In impurities. Further, grazing incidence x-ray scattering measurements of ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}{\mathrm{As}}_{1-y}{\mathrm{N}}_y/\mathrm{GaAs}$ heterojunctions provide direct evidence that the ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}{\mathrm{As}}_{1-y}{\mathrm{N}}_y$ thin films can indeed be lattice matched to GaAs substrates resulting in a reasonably smooth heterointerface.

• Received 4 February 1999

DOI:https://doi.org/10.1103/PhysRevB.60.13605