Photoluminescence from Single Semiconductor Nanostructures

Abstract

We review some recent results in the spectroscopy of single CdSe nanocrystal quantum dots. By eliminating the effects of inhomogeneous broadening and ensemble averaging, single nanocrystal spectroscopy has revealed many new and previously unexpected physical phenomena. Among those discussed in this review are ultra-narrow emission lineshapes (~600´narrower than ensemble spectra), a highly polarizable emitting state in the presence of strong local electric fields, line broadening as a result of environmental fluctuations, and shifting of the emission spectra over a wide range of energies (from less than 300 meV to 80 meV). In addition, polarization spectroscopy of single nanocrystals has revealed the presence of a theoretically predicted two-dimensional transition dipole moment oriented in the xy plane of the nanocrystals. As a result, it is, in principle, possible to use polarization spectroscopy to determine the three-dimensional orientation of individual nanocrystals. These and other studies of single quantum dots have provided us with significant insight into the detailed physics and dynamics of this unique and fascinating physical system.

Blueing, Bleaching, and Blinking of Single CdSe/ZnS Quantum Dots

“…This is in agreement with previous measurements, which show that over longer time periods random spectral diffusion can result in shifts of up to 10 nm. [38,39] Contrary to the situation in air, there is only random spectral diffusion in time and no shift to shorter wavelengths is observed. Photobleaching of the QDs in nitrogen sets in after much longer times, around 10 min on average for both batches (see Table 1).…”

Light‐Emission Performance of Silicon Nanocrystals Deduced from Single Quantum Dot Spectroscopy

“…[2] SNS makes it possible not only to overcome the inhomogeneous broadening of ensemble spectra but also reveals new phenomena such as emission intermittency (ON-OFF blinking), spectral diffusion, and polarization. The application of SNS to single silicon nanocrystals (SiNCs) is still not fully explored because of technical difficulties of sample preparation and the inherently low emission rate of the S-band luminescence of SiNCs.…”

Sterically induced shape control of magnetite nanoparticles

“…Much effort has been focused on synthesis of uniform nanoparticles with various shapes, because the physical and chemical properties of materials depended not only on the chemical composition but also on their size and shape [1][2][3][4]. Pyrolysis method is one important method to synthesize shape and size controlled high-quality nanoparticles in the recent years [5][6][7].…”