Amplified Spontaneous Emission in Close-Packed Films of Semiconductor Nanocrystals Using Picosecond Excitation
✍ Scribed by C.E. Finlayson; D.M. Russell; C.M. Ramsdale; D.S. Ginger; C. Silva; N.C. Greenham
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 92 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1616-301X
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✦ Synopsis
We present experimental observations of line-narrowing of the photoluminescence in close-packed thin films of CdSe nanocrystals with epitaxial ZnS shells, under excitation from a pulsed source of 100 ps duration, both at 77 K and at room temperature (RT). Atomic force microscopy (AFM) of these films reveals them to be optically flat to less than 1 % of the emission wavelength and we propose that waveguiding and amplified spontaneous emission is the principal mechanism for line-narrowing. We observe that line-narrowing is assisted by the use of films with a bimodal distribution of nanocrystal sizes, where the excited state population is concentrated on the larger nanocrystals due to energy transfer.