Microanalysis of high-dose oxygen-implanted germanium

Abstract

High-dose ion implantation is being increasingly used to produce buried oxide layers in silicon for high speed CMOS and VLSI applications. Ion implantation into germanium has been used to control optical properties. Germanium implanted with high dose oxygen is a promising material for photodetectors and solar energy converters. In the present study the structural changes in germanium caused by high dose oxygen implantation, giving low reflectivity in the far-UV and visible, were characterized by HREM and high spatial resolution AEM.The single crystal n-type germanium {111} wafers were implanted with O+ ions to doses of lx1017 to 1.5xl018 cm-2 at 45 keV. The implantation temperature was estimated to be about 400°C. The absorption behavior of the implanted samples was measured by Infrared (IR) spectroscopy. The compositional profiles of implanted layers were obtained by Rutherford Backscattering Spectrometry (RBS) and position-resolved EELS. Cross-sectional TEM samples for microstructural characterization were prepared by mechanical polishing and ion milling. A Philips 400ST/FEG analytical microscope was used for nanoprobe experiments, at 100 kV. Microstructural investigation was performed using ISI-002B and JEM-2000FX microscopes, at 200 kV.