Optical Properties of Semiconductor Nanocrystals

Abstract

Low-dimensional semiconductor structures, often referred to as nanocrystals or quantum dots, exhibit fascinating behavior and have a multitude of potential applications, especially in the field of communications. This book examines in detail the optical properties of these structures, giving full coverage of theoretical and experimental results, and discusses their technological applications. The author begins by setting out the basic physics of electron states in crystals (adopting a 'cluster-to-crystal' approach), and goes on to discuss the growth of nanocrystals, absorption and emission of light by nanocrystals, optical nonlinearities, interface effects, and photonic crystals. He illustrates the physical principles with references to actual devices such as novel light-emitters and optical switches.

Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone

“…[19] However, it is clear that the slope of the curves in Figure 4 should increase with increasing quantum numbers of the orbitals involved, which is exactly what is observed. Furthermore, the slope of the different transitions is also determined by the effective masses of electrons and holes.…”

“…As was mentioned above, the energies of transitions a to z increase (nearly) linearly with D À1.5 and extrapolate to 0.28 eV, with an increasing slope for higher energy transitions. Effective mass theory yields the following expression [19][20][21] for interband transitions with electrons and holes in the same orbitals (e.g. 1S h 1S e , 1P h 1P e , …):…”

“…[19] E g , " h, e, and e in correspond to the fundamental bandgap, Planck s constant, the electronic charge, and the dielectric constant inside the nanocrystal, respectively. Neglecting the last term (because of the high e in of PbSe), we find the following slope of the energy with respect to D À2 :…”

Quantum Optics: Colloidal Fluorescent Semiconductor Nanocrystals (Quantum Dots) in Single-Molecule Detection and Imaging

“…Interested readers should consult textbooks on quantum mechanics, solid-state physics, or QDs (Atkins and Friedman 1997;Gaponenko 1998;Kittel 1996) for an in-depth discussion.…”

Photosensitivity Enhancement with TiO2 in Semitransparent Light-Sensitive Skins of Nanocrystal Monolayers

“…We note that another means of decreasing the recombination probability of photogenerated electrons and holes in these devices relies on surface passivation of the NCs. 1 Indeed, charges encounter high potential barriers due to the ligands passivating the NCs' surface. During the film assembly, the NC solution was rigorously stirred to prevent precipitation.…”