engleski

Raman study of "boson" peak in ion-implanted GaAs: Dependence on ion dose and dose rate

Here we present a systematic Raman study of the "boson peak" which appears in GaAs during the processes of amorphization. We investigate the influence of the ion dose and dose rate. The findings were interpreted in the fractal model and correlated with recent analysis of ion-induced damage from Raman and ion channeling measurements. The Raman spectra were decomposed on phonon-fracton curve and Gaussian bands by a fitting procedure. The crossover frequency omegacol between phonon and fracton regimes and the fractal exponent (sigma+d-D)d/D shows a pronounced dependence on applied ion dose and weak dependence on dose rate. Evolution of the fractal component is compared with ion channeling measurements and Raman spectra of phonon bands. The fractal component is strongly dependent on ion dose as is the amorphous component and is weakly dependent on dose rate. It indicates that the fractal component is not connected with point crystalline defects, to which ion channeling is particularly sensitive. The fractal correlation length and spectral dimension d, calculated from the crossover frequency and fractal exponent, changes from =6 A and d~=0.2 for weakly damaged samples, to =10 A and d~=0.8 for completely amorphized samples (7 References).

Boson peak ; Raman ; amorphous materials

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