The Raman spectroscopy of neutron transmutation doping isotope (74)Germanium nanocrystals embedded in SiO2 matrix

We have succeeded in doping arsenic (As) impurities into isotope germanium nanocrystals (nc-Ge-74) uniformly dispersed in a SiO2 matrix by using the neutron transmutation doping (NTD) method. The samples' inner structural transmutation is studied by combining Raman scattering, Xray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscope (TEM) methods. The Raman spectrum of the doped sample exhibits a relative intensity increase of the low frequency tail, blue shift of the main Raman peak (similar to 300 cm(-1)) and a high frequency tail, while the undoped sample does not. Together with the XRF, XPS and TEM, we believe that the relative intensity increase of the low frequency tail arises from an increase of amorphous Ge-74 (a-Ge-74) induced by the irradiation damage. The blue shift of the main Raman peak comes from the mismatch of the crystal lattice which arose from the As impurity introduction. And the high frequency tail is due to transmuted-impurities (As) in the nc-Ge-74 which was introduced by NTD. (c) 2006 Elsevier Ltd. All rights reserved.