Evolution of photoluminescence life-times distribution in Si-QD/SiO₂ multilayer films

College of Physics Science and Technology, Hebei University, Baoding 071002, P.R. China

^a e-mail: yuwei_hbu@126.com
^b e-mail: fugs@hbu.edu.cn

Received: 12 March 2013
Revised: 8 May 2013
Accepted: 14 May 2013
Published online: 11 June 2013

Abstract

Si-rich oxide/SiO₂ multilayer films with different N₂O flow rates have been deposited by plasma enhanced chemical vapor deposition technique, and Si quantum dot (Si-QD)/SiO₂ multilayer films are obtained by 1100 °C annealing. Steady photoluminescence (PL) spectra show that the main optical emission mechanism changes from quantum confinement effect of Si-QDs to interface defect states with increasing the flow rate of N₂O. Curve fittings of time-resolved PL spectra show that two log-normal decay time distribution bands are obtained, and both the most frequent life-times decrease with increasing the flow rate of N₂O, while increase with the red shift of detecting wavelength. Analyses indicate that defect states density and size distribution of Si-QDs strongly influence the PL decay properties.