Observation of low energy acoustic phonon modes at low temperature from stressed Si nanoclusters

Abstract

Photoluminescence spectroscopy has been used to study the emission characteristics of stressed Si nanoclusters formed in Si over a wide temperature range of 6 to 300 K. The results show splitting of single narrow peak to four sharp lines with lowering of temperature to 6 K. The four lines could be identified as a zero-phonon line (ZPL), one and higher optical phonon-assisted lower energy lines. The observed ZPL has a linewidth as sharp as ∼13 meV at ∼6 K. The low temperature measurements further reveal the interaction of ZPL with low energy acoustic phonons as low as 7 ± 1 meV, at low temperature, below 100 K. This has only been seen earlier in the case of single Si quantum dots. © 2015 IOP Publishing Ltd.