Low temperature UV oxidation of SiGe for preparation of Ge nanocrystals in SiO2

Abstract

We describe a novel technique fully compatible with silicon microelectronic technology for the synthesis of Ge nanocrystals. The approach followed involves UV-assisted low temperature dry oxidation of a strained Si0.8Ge0.2 layer. Initially, oxidation results in the selective formation of SiO2 under which accumulates a Ge-rich SiGe layer. Further irradiation and oxidation of this structure result in the incorporation of Ge nanocrystalline regions from 2 to 8 nm in diameter into the growing SiO2 layer. These Ge nanoparticles exhibit visible photoluminescence in the 550-800 nm range. The temperature of only 550 °C employed in our process is significantly less than the 800-850 °C levels necessar..