Abstract:
GaAs₁₋ₓNₓ alloy films (0 ≤ x ≤ 0.055) grown on GaAs (001) substrates by metalorganic vapor phase epitaxy (MOVPE) using TBAs and DMHy as As and N precursors, respectively, were investigated by Raman spectroscopy. It was found that, with incorporating N up to x = 0.055, a single N-related localized vibrational mode (LVM) is observed at around 468-475 CM⁻¹. We investigated the N-related LVM Raman intensity (I [subscript LVM]) and frequency (N (ѡ [subscript LVM])) as a function of N concentration. Both the I [subscript LVM] and the ѡ [subscript LVM] were found to rise for theGaAs₁₋ₓNₓ films with higher N incorporation. It is also evident that the N concentration in the GaAs₁₋ₓNₓ grown films determined by Raman spectroscopy technique (X [subscript Raman]) exhibits a linear dependence on the N concentrations determined by the high resolution X-ray diffraction (HRXRD) x [subscript XRD]. Our results demonstrate that the linear dependence of the X [subscript Raman]) on the x [subscript XRD] provides a useful calibration method to determine the N concentration in dilute GaAs₁₋ₓNₓfilms <0.005). Although, the FTIR spectra of GaAs N films can not be observed due to the limit of the instrument. On the other hand, the 8.5K-PL peak energy of the GaAs N films was varied from 1.39 to 0.97 eV with increasing N content up to 5.28%. A large red shift in PL peak position demonstrates a large bowing parameter of the GaAs₁₋ₓNₓalloy layers due to the incorporation of N into the lattice.
