GERMANIUM AND SILICON/GERMANIUM NANOPARTICLES ENCAPSULATED IN AMORPHOUS SILICON MATRIX FOR PHOTOVOLTAIC APPLICATIONS

Abstract

Thin films prepared by deposition of nanoparticles on the surface of hydrogenated silicon were studied with aim to optimize properties for optoelectronic applications. Two techniques were used to prepare the nanoparticles –ArF Laser Ablation and MBE resp. high vacuum evaporation. Broad range of deposition conditions (e.g. precursor pressure, temperature and laser fluence) was studied. Interesting and utilizable optoelectronic properties were observed at multilayered films composed of Germanium nanoparticles. The Ge NPs were deposited immediately (in situ) after deposition of the amorphous silicon layer by Plasma Enhanced CVD without exposing the underlying layer to ambient air in the case of Laser Ablation. In the case of MBE the Ge NPs were deposited ex situ, but after previous deposition of amorphous silicon. The deposited material was characterized by means of Raman and photoelectron spectroscopy techniques. Transmission, scanning and atomic force microscopies were used for more detailed description of the prepared layers.