Thermal Carrier Escape and Capture in CdTe Quantum Dots

Abstract

We studied optical properties of CdTe quantum dots (QDs) by steady-state and time-resolved photoluminescence spectroscopy. By changing the excitation power at high temperatures (about T = 70 K) we can significantly influence the distribution of excitons within the quantum dot ensemble. The effect manifests itself by a large (100 meV) red shift of the PL emission energy when the excitation power decreases by five orders of magnitude. This red shift is accompanied by a decrease of the linewidth of the emission band. We discuss these effects in the frame of a model of thermally induced redistribution of carriers between the zero-dimensional electronic states within the quantum dot ensemble. Moreover, we found that the exciton decay time of the QD emission increases dramatically when the number of excitons injected into the system is reduced.

Laser irradiation effects on the CdTe/ZnTe quantum dot structure studied by Raman and AFM spectroscopy

“…10 The spectra are representative for the samples under study. As it was shown in several papers 7,8,[11][12][13][14][15][16] for many layers of CdTe QDs like in present case (6 ML) the QD signal can dominate the PL signal. Detailed analysis of PL measurements will be given elsewhere.…”

Resonant photoionization absorption spectra of spherical quantum dots

“…It is the direct Coulomb interaction that (i) increases the peak heights, (ii) shifts the position of the peaks to higher energy, (iii) broadens the peaks and (iv) makes the peaks with higher resonance photon energy more effective. Note that in part these features manifest themselves in the experimental results in [5]. Besides, the exchangecorrelation interaction affects the photon absorption considerably by decreasing the effect of direct Coulomb interaction (see figure 2, especially (e) and (f) which show that the exchange-correlation interaction completely suppresses the absorption for R > 150 Å due to (1; 1) → (3; 2) res and (1; 1) → (4; 0) res transitions).…”

“…Photon absorption properties of QDs have been investigated experimentally in many works [2][3][4][5][6][7][8][9][10][11]. A number of theoretical works were devoted to the investigation of electronic structure of QDs and QD arrays [12][13][14][15][16], and optical transitions and absorption spectra of QDs due to electron transitions between bound states (bound-bound transitions) as well as between bound and continuous (or free) states (bound-free or photo-ionization transitions) of electrons [17][18][19][20][21][22][23][24][25].…”

GaAs Quantum Dot Confined with a Woods–Saxon Potential: Role of Structural Parameters on Binding Energy and Optical Absorption

“…In addition to the geometry and shape of the confining potential, the incorporation of a hydrogenic impurity in QDs can modulate electronic and optical absorption coefficients (OACs) due to the electrostatic attraction between the free electrons and the impurity [26][27][28][29][30][31][32]. Previous work on OACs in QDs has focused on both theoretical and experimental studies [33][34][35][36]. For instance, Schrey et al studied the optical absorption of quantum dots in photodetectors and analyzed the effect of QD size on their minibands [37].…”