Quantum Confined Intense Red Luminescence from Large Area Monolithic Arrays of Mesoporous and Nanocrystal-Decorated Silicon Nanowires for Luminescent Devices

摘要

We report intense red luminescence from mesoporous n(+)-Si(100) nanowires (NWs) and nanocrystal-decorated p-Si NWs fabricated using electroless metal assisted chemical (MAC) etching. n(+)-Si NWs are composed of a labyrinthine network of silicon nanocrystals in a random mesoporous structure. p-type Si(100) NWs exhibit solid core structure, with a surface roughness that contains surface-bound nanocrystals. Both mesoporous n(+)-Si NWs and rough, solid p-Si NWs exhibit red luminescence at similar to 1.7 and similar to 1.8 eV, respectively. Time-resolved photoluminescence (PL) measurements indicated long (tens of mu s) radiative recombination lifetimes. The red luminescence is visible with the naked eye and the red light is most intense from mesoporous n(+)-Si NWs, which exhibit a red-shift in the emission maximum to 1.76 eV at 100 K. The red PL from monolithic arrays of p-type NWs with nanocrystal-decorated rough surfaces is comparatively weak, but originates from the surface bound nanocrystals. Significant PL intensity increase is found during excitation for mesoporous NWs. X-ray photoelectron spectroscopy identifies a stoichiometric SiO2 on the rough p-Si NWs with a SiOx species at the NW surface. No distinct oxide is found on the mesoporous NWs. The analysis confirms that long life-time PL emission arises from quantum confinement from internal nanoscale crystallites, and oxidized surface-bound crystallites, on n(+)and p-Si NWs respectively. (C) The Author(s) 2015. Published by ECS.