Nano-cluster formation in Ge plus Sn implanted SiO2 layers

Thermally grown, 200 rim thick layers of SiO2 were double implanted with Ge+ and Sn+ ions in turn and the resulting SiO2(Ge+Sn)/Si structures were annealed at 400-900 degrees C for 30 min. Using transmission electron microscopy (TEM) and electron diffraction (TED), clear evidence is found that the layers of SiO2 Contain Ge and Sn nano-clusters. Depending on the conditions of implantation and thermal treatment the average size and the density of the nano-clusters vary within 10-20 nm and 10(10)-10(11) cm(-2) respectively. Rutherford backscattering spectroscopy (RBS) demonstrated that no visible redistribution of Ge and Sri takes place after thermal treatment at 400800 degrees C and only slow segregation of dopants at the SiO2/Si interface occurs at 900 degrees C for the sample implanted with high ion fluence. The cathodoluminescence (CL) spectra obtained from the SiO2(Ge+Sn)/Si structures contain intensive peaks in blue and near-infrared regions. (c) 2006 Elsevier B.V. All rights reserved.