Interband and intraband optical transitions in InAs nanocrystal quantum dots: A pseudopotential approach

Abstract

Published paperAn atomistic pseudopotential method is used to investigate the electronic and optical properties of spherical InAs nanocrystals. Our calculated interband (valence-to-conduction) absorption spectra reproduce the features observed experimentally both qualitatively and quantitatively. The results relative to intraband (valence-to-valence and conduction-to-conduction) absorption successfully reproduce the recently measured photoinduced absorption spectra, which had so far been addressed only qualitatively. They exclude the hypothesis of a thermal activation process between dot-interior-delocalized hole states to explain the temperature dependence observed experimentally. Furthermore, based on the agreement of our data with the experimental valence intersublevel transitions and the almost complete overlap of the latter with STM measurements, we question the simplistic attribution of the observed STM peaks obtained for negative bias.

Intersubband optical absorption coefficient changes and refractive index changes in a two-dimensional quantum pseudodot system

“…The interest in the study of the physical properties of confined quantum systems such as quantum wells, wires and dots has increased with the recent progress in semiconductor nanotechnology [1][2][3]. In these structures, precise engineering enables us to confine the charge carrier motion in one, two or three dimensions, which allows us to control the physical properties of the structures.…”

The effect of small elongations on the electronic and optical signatures in InAs nanocrystal quantum dots

“…We found, as in the case of previous tight binding calculations [21], that the spacing between the two uppermost valence band states (ranging from 20 to 40 meV for the NC sizes considered here) was too small compared to the experimental data. Based on the assumption of state-independent quasi-particle polarization selfenergies, we proposed an alternative interpretation of the STM results in terms of the spacing between the DOS peaks we calculated for InAs dots [17]. In this approximation, therefore, the calculated DOS for elongated structures shown in Figure 1 could provide some insight into the nature of the experimental samples.…”

“…We see that the elongation has two main effects: as σ increases, the density of states in both conduction and valence bands increases and the single-particle band gap E g shifts to the red. We have questioned in the past [17] the simple interpretation of the STM peaks measured by Banin et al [20] for negative bias, in terms of tunnelling between single hole states. We found, as in the case of previous tight binding calculations [21], that the spacing between the two uppermost valence band states (ranging from 20 to 40 meV for the NC sizes considered here) was too small compared to the experimental data.…”

“…This approach (and very similar EPM-based ones) has proved highly successful in the past in interpreting the optical properties of spherical nanostructures made of different materials such as CdSe [12,13], InP [12,14], PbSe [15], and InAs [16,17]. However, so far it had been applied to the investigation of elongated NCs made of CdSe [18] and InP [19] only.…”

Poly(vinyl-pyrrolidone) assisted hydrothermal synthesis of flower-like CdS nanorings

“…CdS, which is one of the most classical direct band gap II-VI semiconductors [3,4], is now widely used in light-emitting diodes, photocatalyst, solar cell, single charge memories, luminescent nanocomposites, and diagnostic agents in medicine [5][6][7][8][9][10]. Over the past few years, much effort has been paid on the fabrication of CdS with specialized size and morphology [11,12].…”