Electronic structure and luminescence of low-dimensional semiconductors

Abstract

AbstractUnlike all of the previous chapters, this one is devoted to low-dimensional semiconductor structures (quantum wells, quantum wires and quantum dots-nanocrystals). Basic classification of these structures is outlined and densities of electronic states are described. A detailed theoretical treatment of electronic states and exciton effects in quantum wells, both with infinite and finite barriers, is presented in effective-mass approximation. Strong and weak quantum confinement limits are discussed. Selection rules for optical transitions in quantum wells are outlined and optical absorption and emission spectra are compared. Specificity of exciton behaviour is stressed. Quantum dots with spherically symmetric potential are described in strong and weak quantum confinement regime. Salient luminescence features of quantum dots are summarized and illustrated via typical examples. Briefly mentioned are other interesting luminescence-related phenomena: phonon bottleneck, excitons indirect in real space, enhancement of nano-luminescence by metal nanoparticles and exciton multiplication.