Room-temperature observation of size effects in photoluminescence of Si _0.8Ge _0.2/Si nanocolumns prepared by neutral beam etching

We report the room-temperature observation of clear size effects in photoluminescence of ensembles of SiGe/Si double-quantum-well nanocolumns. A silicon thin layer (~100 nm) containing two 3-nm-thick Si _0.8Ge _0.2 layers was etched into an ensemble of ~100nm tall nanocolumns standing vertically on the 200-nm-thick silicon-on-insulator layer. A clear shift of photoluminescence peak positions appearing at around 1.8 eV has been observed with varying average diameter of the nanocolumns between 18 and 24 nm.