Effect of high-energy light-ion irradiation on SI-GaAs and GaAs:Cr as observed by Raman spectroscopy

The structural evolutions of high-energy (50 MeV) lithium ion (Li3+) irradiated undoped semi-insulating GaAs (SI-GaAs) and chromium-doped SI-GaAs (GaAs:Cr) were investigated by Raman measurements. It is shown that high-energy Li3+ irradiation causes amorphization beyond a fluence of 3 x 1013 ions/cm2 in undoped SI-GaAs. Interestingly, the same fluence of ions does not seem to affect the crystallinity in GaAs:Cr appreciably. The effect of ion irradiation on the change in lattice ordering and anharmonicity of the phonon modes of undoped SI-GaAs and GaAs:Cr is also compared. Copyright (C) 2011 John Wiley & Sons, Ltd.