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Unpolarized Raman spectra of as-grown and annealed . Both spectra show features arising from second order GaAs-like longitudinal and transverse optical phonons from 500 to , and first order GaN-like phonons at . In addition, we observed Raman features , and at frequencies 410 and , respectively, the intensities of which are significantly suppressed after annealing. The reduction in observed by NRA suggests these Raman signatures are attributed to N interstitials.
(a) Electron mobility, , and (b) free carrier concentration, , for bulk GaAsN:Te and GaAs:Te films as a function of annealing temperature. In GaAsN: Te (GaAs:Te) films, , and increase substantially (remain constant) with increasing annealing-.
Resistivity, , as a function of measurement- for an as-grown GaAs:Te film and GaAsN:Te films before and after annealing. For as-grown films with decreasing measurement-, increase substantially (GaAsN:Te) or remains constant (GaAs:Te).
Free carrier concentration, , as a function of inverse temperature for films annealed at different temperatures. Two distinct -dependent regimes of are apparent: , increases exponentially with increasing ; , is independent of . In order to use a two-level system formalism to extract the activation energy of N-induced deep donor state, is also plotted in open circles for .
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