Photoluminescence of Ge Nanoclusters in Ion Implanted SiO 2
- PDF / 234,653 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 58 Downloads / 220 Views
M8.28.1
Photoluminescence of Ge Nanoclusters in Ion Implanted SiO2 J.M.J. Lopes, F.C. Zawislak, M. Behar, P.F.P. Fichtner1, L. Rebohle2, W. Skorupa2 Instituto de Física – UFRGS, Cx. Postal 15051, 91501-970 Porto Alegre, Brazil 1 Departamento de Metalurgia, Escola de Engenharia − UFRGS, Caixa. Postal 15051, 91501-970 Porto Alegre, Brazil 2 Forschungszentrum Rossendorf e.V. 01314 Dresden, Germany ABSTRACT 180 nm thick SiO2 films produced by wet oxidation of (100) Si wafers were implanted at room temperature with 120 keV Ge+ ions at a fluence of 1.2×1016 cm−2 in order to allow the formation of Ge nanoparticles upon post implantation thermal annealings within the interval 400°C ≤ T ≤ 900°C. The size and depth distribution of the Ge nanoparticles were characterized by Transmission Electron Microscopy and Rutherford Backscattering Spectrometry. In addition, the room temperature photoluminescence (PL) bands of the nanoparticles system were studied in the regions of the blue-violet and ultra-violet emissions. The mean diameter of the nanoclusters increases from 2.2 nm at 400°C to 5.6 nm at 900°C. Concomitantly, the blue-violet PL intensity increases by a factor of 12 within the same temperature interval. The results are discussed in terms of possible atomic mechanisms involved in the coarsening behavior and leading to the formation of luminescent centers.
INTRODUCTION Since the discovery of intense visible light emission in porous Si1, a significant amount of efforts has been dedicated to the production of nanostructured Si-based systems2-4. Several studies have used ion implantation of group IV elements in SiO2 and heat treatment to obtain nanostructures exhibiting photoluminescence (PL). This is an alternative of special interest because of its compatibility with the Si technology in the fabrication process. The red or infrared PL of Si-implanted oxides with post-annealing at diverse temperatures has been reported by various authors5-8. Recently Fernandez et al.8 have suggested that the PL emission of Si nanocrystals embedded in SiO2 is due to a fundamental transition located at the Si-SiO2 interface with the assistance of a local Si-O vibration. In other studies, where visible and ultraviolet (UV) PL from Si-, Ge- and Sn-implanted oxides are obtained there is a general agreement that the emissions are caused by oxygen deficiency centers (ODCs) created during the implantation and annealing processes9-13, and located in the interfacial region between the cluster and the oxide matrix. However, a concrete understanding of the PL-emitter structure involving nanoclusters and ODCs is still under current debate. In the present work, the formation and coarsening behavior of Ge nanoclusters in SiO2 are investigated using a combination of Rutherford backscattering spectrometry (RBS) and transmission electron microscopy (TEM). The results obtained are correlated with the intensity of PL emission measurements and discussed in terms of possible atomic mechanisms involved in the coarsening behavior and leading to the formation of the
Data Loading...
