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GaN-related alloys have been settled up as the preferred semiconductors for the development of emission optoelectronic devices for the green-to-violet portion of the visible spectrum. GaAsN ternary alloys in the GaAs-rich side have shown their potentiality for near infrared devices such as semiconductor lasers, using their unique property of a reduction in the band gap energy down to less than 1.55 microns for small N concentrations below 5% in the alloy. On the other side, GaNAs alloys in the GaN-rich side have been theoretically predicted to have a sharp reduction in the band gap energy from the value for GaN (3.42 eV for the hexagonal phase at room temperature) down to values below 1 eV, when the N concentration changes from 100% to about 80%, owed to a quite large bowing parameter. We have use the radio frequency sputtering deposition technique to grow GaN(x)As(1-x) thin films on Corning glass slides and Si wafers, with high N concentrations in order to obtain large band gap energies. The control in the N incorporation in the film was obtained by controlling the r. f. power used in the deposition chamber. We present results on the structural and optical characterization of a series of samples grown using variable r. f. powers in the range: 140-240 W at substrate temperatures around 300 C. Optical absorption spectra show a shift of the absorption edge to higher energies as the r. f. power decreases which correspond to an increase in the film N concentration. X-ray diffractograms show the presence of a GaAs phase, the hexagonal and cubic GaN phases, and a GaNAs phase. Los temperature photoluminescence (PL) spectra show emission bands associated to the GaN phase, and at lower energies some bands that can be assigned to emission from the ternary GaNAs phase. We analyze these results for the samples with different N concentrations corresponding to different band gap energies, and also in terms of the amorphous or crystalline nature of the substrate used. |