The paper presents the brief review of published results as well as the original study of photoluminescence (PL) and
Raman scattering of core-shell CdSe/ZnS quantum dots (QDs) with radiative interface states. First commercially
available CdSe/ZnS QDs with emission at 525 nm (2.36 eV), 565 nm (2.20 eV), 605 nm (2.05 eV) and 640 nm (1.96
eV) covered by PEG polymer have been compared in nonconjugated states. PL spectra of nonconjugated QDs are
characterized by a superposition of PL bands related to exciton emission in CdSe cores and to hot electron-hole
emission via high energy states (2.00, 2.20, 2.37, 2.75 and 3.04 eV). The high energy states were studded using QDs of
different sizes and at different temperatures. It is shown that these PL bands related to interface states. Then the
CdSe/ZnS QDs with the color emission 525nm and 605 nm have been conjugated with bio-molecules - ovarian cancer
(OC 125) and anti Interleukin 10 (IL-10) antibodies, respectively. It is revealed that the PL spectrum of bioconjugated
QDs has changed dramatically with essential decreasing the hot electron-hole recombination flow via interface states.
The variation of PL spectra at the bioconjugation is explained on the base of electrostatic interaction and re-charging of
QD interface states. The Raman scattering study of nonconjugated and bioconjugated QDs has shown that mentioned
antibodies are characterized by the dipole moment that provokes the surface enhance Raman scattering effect in
bioconjugated QD samples as well.
This paper presents briefly the history of the study of Si quantum dot (QDs) structures and the advances of different
applications of Si quantum dots (QDs) in quantum electronics, such as: Si QD light emitting diodes, Si QD solar cells
and memory structures, Si QD based one electron devices and double QD structures for spintronics [1].
Nanoscaled Si (Ge) systems continue to be of interest for their potential application as Si (Ge) based light emiting
materials and photonic structures. Optical properties of such systems are sensitive to nanocrystallite (NC) size
fluctuations as well as to defects effects due to large surface to volume ratio in small NCs. Intensive research of Si (Ge)
NCs is focused on the elucidation of the mechanism of radiative recombination with the aim to provide high efficient
emission at room temperature in different spectral range. The bright visible photoluminescence (PL) of the Si (Ge)-SiOX
system was investigated during last 15 years and several models were proposed. It was shown that blue (~2.64 eV) and
green (~2.25 eV) PL are caused by various emitting centers in silicon oxide [1], while the nature of the more intensive
red (1.70-2.00 eV) and infrared (0.80-1.60 eV) PL bands steel is no clear. These include PL model connected whit
quantum confinement effects in Si (Ge) nanocrystallites [2-4], surface states on Si (Ge) nanocrystallites, as well as
defects at the Si/SiOX (Ge/SiOX) interface and in the SiO2 layer [5-11]. It should be noted, that even investigation of PL
on single Si quantum dots [12] cannot undoubtedly confirm the quantum confinement nature of red emission.
Model consideration is given to explain observed multi-shell emission spectra from InAs quantum dots embedded in GaAs or InGaAs. The shell model is based on the quantization of kinetic energy of lateral motion of carrier in the dot. 2-D oscillator is calculated on the basis of effective mass approximation. Profiles of inter-level separation are classified into categories that are connected with the lateral confining potential. Comparison is carried with experimental data on InAs/InGaAs quantum dot structures of the DWELL type (dot-in-a-well).
Photoluminescence spectra are investigated of InAs/InGaAs QD structures prepared be MBE on GaAs substrates in a range of pumping power density up to 0.6 kW/cm2. Multiple spectra band are observed corresponding to electron shells in atom-like dots. Identification of shells is proposed on the basis of spherical oscillator model. Energy diagram of dots is proposed taking into account identical temperature dependence of PL intensity in three lowest spectral bands.
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