The effects of ion-implantation damage on the first-order Raman spectra of GaP

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Abstract
We have analyzed the effects of ion-implantation-induced damage on the first-order Raman spectra of GaP, and have correlated changes in the Raman spectra with direct measurements of implantation-induced surface stresses. We find that, at low ion fluences, the effects of implantation damage are to produce point defects that remove free carriers from doped material and to produce stresses in the undamaged regions. In this regime, the stress-induced shifts of the Raman lines can be predicted from the known elastic constants of undamaged GaP. At intermediate fluences, implantation damage alters the elastic properties of GaP so that the stress-induced shifts of the Raman lines are less than those predicted from the properties of the undamaged crystal. At higher doses, implantation-induced surface stresses exceed the elastic limit of the damaged material. This plastic deformation of the implanted surface is accompanied by a rapid broadening of the phonon lines in the first-order Raman spectra.