"Estudo do efeito da anarmonicidade e desordem induzida em filmes de GaAs1-xNx, por espectroscopia Raman"

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

Raman spectroscopy was used to investigate the vibrational properties in thermally treated and as grown thin films of GaAs1-xNx alloys, with 0,0144 ≤ ≤ 0,0370. Raman spectra exhibit the presence of two GaAs1-xNx characteristic modes. The redshift of the GaAs-like longitudinal-optic phonon (LO1) frequency and the blue shift of GaNlike longitudinal-optic phonon (LO2) frequency are observed with increasing N concentration. It was verified that these behaviors are associated with lattice strain, alloy effects, non-intentional doping and the loss of long range crystalline order. The effect of compositional disorder in GaAs1-xNx alloys has been studied by analyzing the broadening asymmetric, and line shift of the first-order LO1 mode. It is found that the line shape and peak shift of LO1 mode in GaAs1-xNx alloys can be well described by the spatial correlation model. The temperature dependence of phonon linewidth and energy of LO1 modes are analyzed in terms of anharmonic effect induced by thermal and compositional disorder. It was observed that the anharmonicity in the GaAs1-xNx alloys is higher than that in GaAs-bulk. In addition, both thermal and compositional disorder-induced anharmonicities lead to an appreciable change of the LO1 phonon lifetime.

ASSUNTO(S)

anarmonicidade desordem fisica espectroscopia

ACESSO AO ARTIGO

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