Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)
- Universite Francois Rabelais de Tours, CNRS CEA, INSA-CVL, GREMAN UMR 7347, 37071 Tours Cedex 2 (France)
- pSiMedica Ltd., Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ (United Kingdom)
- Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)
The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO{sub 2} solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yield (>32% at room temperature) has been achieved, prompting the need for further detailed studies to establish the dominant causes of such an improvement.
- OSTI ID:
- 22591581
- Journal Information:
- Applied Physics Letters, Vol. 108, Issue 15; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of resistivity and current density on photoluminescence in porous silicon produced at low HF concentration.
Optical absorption and photoluminescence studies of free-standing porous silicon films with high porosities