Time-Resolved Photoluminescence Study of Silicon Nanoporous Pillar Array

A silicon nanoporous pillar array (Si-NPA) is thought to be a promising functional substrate for constructing a variety of Si-based optoelectronic nanodevices, due to its unique hierarchical structure and enhanced physical properties. This makes the in-depth understanding of the photoluminescence (PL) of Si-NPA crucial for both scientific research and practical applications. In this work, the PL properties of Si-NPA are studied by measuring both the steady-state and time-resolved PL spectrum. Based on the experimental data, the three PL bands of Si-NPA, i.e., the ultraviolet band, the purple-blue plateau and the red band are assigned to the oxygen-excess defects in Si oxide or silanol groups at the surface of Si nanocrystallites (nc-Si), oxygen deficiency defects in Si oxide, and band-to-band transition of nc-Si under the frame of quantum confinement combining with the surface states like Si=O and Si-O-Si bonds at the surface of nc-Si, respectively. These results may provide some novel insight into the PL process of Si-NPA and may be helpful for clarifying the PL mechanism.