Temperature-dependent photoluminescence properties of porous silicon nanowire arrays

Luminescent porous silicon nanowire arrays are prepared through metal-assisted chemical etching. Photoluminescence (PL) and cathodoluminescence (CL) reveal that both the nanowire arrays and individual nanowire exhibit intense orange emission around 1.9 eV at room temperature. The emission linewidth increases monotonously and significantly with decreasing temperature. Combined with PL decay measurements, the results indicate that there are two transitions contributing to the broad emission at low temperatures. In addition, negative thermal quenching of the PL intensity due to surface states is observed. A multi-level transition model is proposed to interpret the experimental results. (C) 2011 American Institute of Physics. [doi:10.1063/1.3643047]