Ge nanocrystals in alumina matrix: A structural study

R J Kashtiban, S R C Pinto, U Bangert, A G Rolo, A Chahboun, M J M Gomes, A J Harvey
2010 Journal of Physics, Conference Series  
Germanium (Ge) nanocrystals (NCs) embedded in alumina thin films were produced by deposition on silicon (111) substrates using radio-frequency (RF) magnetron sputtering. By changing growth condition and annealing parameters samples with large and small Ge-NCs were produced. The average size of NCs in the sample with larger NCs was estimated to be 7.2, 30.0 and 7.6 nm, and 5.0, 7.0 and 4.8 nm for the sample with smaller NCs, according to Xray diffraction (XRD), Raman and high resolution
more » ... ion electron microscopy (HRTEM) results, respectively. Both, XRD and Raman peak positions of the larger NCs are shifted to higher angles and larger wave numbers in relation to the Ge bulk values, whereas the Raman peak was red-shifted for the smaller NCs indicating phonon confinement. HRTEM shows twinned structures, which is an indication of relaxation. Strain evaluation of the bigger NCs gave values < 0.5 % which is within the estimated error of the evaluation technique.
doi:10.1088/1742-6596/209/1/012060 fatcat:vwbjuca62fh2zfjozyuejpoqku