Structure and photoluminescence study of silicon based two-dimensional Si2Te3 nanostructures


As an emerging silicon-based two-dimensional (2D) material, vertical and horizontal Si2Te3 nanoplates on various substrates have been deposited by chemical vapor deposition. Structure, composition, and optical properties of these nanostructures are investigated by electron microscopy, x-ray photoelectron emission, energy dispersive x-ray spectroscopy, and temperature dependent photoluminescence. Band gap emissions of Si2Te3 nanoplates containing four noticeable emission peaks, i.e., free exciton, acceptor-bound exciton (A0X), and phonon replicas of A0X, are observed at temperatures below 90 K. The temperature dependent emission intensity of A0X indicates there are two quenching channels, which are associated with thermal quenching and thermal dissociations of A0X to free excitons. Two defect emissions are observed at measurement temperatures from 10 to 300 K, and their peak energies decrease by following the band gap change at low temperature range but increase at high temperature range as the temperature is increased. This abnormal temperature dependent behavior is explained by a combination of band gap shrinkage and thermally induced localization effects of defects at high temperature. This study helps to understand the electronic and optical properties of the unique 2D Si2Te3 nanostructures for potential applications.

Publication Title

Journal of Applied Physics