Narrow gap nitride semiconductors have shown significant promise for a wide range of applications, including long-wavelength light-emitters, high performance electronic devices, and high efficiency solar cells. In the case of GaAsN, a consequence of the large N-As size difference is a predicted limited miscibility on the anion sublattice, which often leads to the formation of GaN-rich nanostructures [1-2]. Dilute GaAsN alloys are typically achieved using low growth temperatures, which enable N incorporation without GaN surface conversion. In addition, conflicting results have been reported regarding the mechanism of N incorporation, and recent optical studies have suggested that the shear deformation potential and/or the binary elastic constants may have an unusual composition dependence . In this talk, I will discuss our recent investigations of the growth, structure, and properties of GaAsN films, using a variety of in-situ and ex-situ measurements. I will present evidence for significant non-substitutional N incorporation and significant bowing of the elastic properties of GaAsN alloys. In addition, I will discuss a new “forbidden window” for GaAsN growth, and its impact on the electronic and optical properties of GaAsN films.
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This work is supported in part by the Department of Energy, through the National Renewable Energy Laboratory Photovoltaics Beyond the Horizon Program, the National Science Foundation (NSF), the Air Force Office of Scientific Research, the TRW Foundation, and NASA-Lewis.