Photoluminescence Mechanism in Silicon Quantum Rods Studied by Time-Resolved Spectroscopy

The photoluminescence (PL) spectrum of Si quantum rods (QRs) shows multiple peaks in the visible region. The PL decay is tri-exponential and decay time monotonically decreases with increasing emission energy. The multi-exponential nature of the PL emission indicates that the rediative recombination occurs through a distribution of localized states. Each of the decay channels are linked with the different bands of emission spectrum. The faster, moderate and slower components of the decay are related to band-to-band, band-to-surface states and within surface states transitions respectively. The observed phenomenon suggests that the visible emission originates from radiative recombination of exciton in the quantum confined nanostructures and oxide related surface states of Si-QR.