کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1546195 | 997610 | 2010 | 6 صفحه PDF | دانلود رایگان |
In two-phase disordered media composed of borosilicate glass with ZnSe or CdS quantum dots, the formation of a phase percolation transition of carriers for near-threshold concentrations that are manifested in optical spectra has been observed. Microscopic fluctuations of the quantum-dot density near the percolation threshold were found that resembled the phenomenon of critical opalescence, where similar fluctuations of the density of a pure substance appear near to a phase transition. It is proposed that the dielectric mismatch between a matrix and ZnSe or CdS quantum dots plays a significant role in the carrier (exciton) delocalization, resulting in the appearance of a “dielectric Coulomb trap” beyond the QD border and the formation of surface states of excitons. The spatial overlapping of excitonic states at the critical density of quantum dots results in a tunneling of carriers and the formation of a phase percolation transition in such media.
Journal: Physica E: Low-dimensional Systems and Nanostructures - Volume 42, Issue 5, March 2010, Pages 1549–1554