Eur. Phys. J. B 54, 471-477 (2006)
https://doi.org/10.1140/epjb/e2007-00027-5

Shape dependent electronic structure and exciton dynamics in small In(Ga)As quantum dots

¹ Institut de Ciències dels Materials, Universitat de València, P.O. Box 22085, 46071 València, Spain
² Instituto de Microelectrónica de Madrid (CNM-CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid, Spain
³ Laboratoire Pierre Aigrain, École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France

Corresponding author: ^a jordi.gomis@uv.es

Received: 25 September 2006
Revised: 1 December 2006
Published online: 3 February 2007

Abstract

We present a study of the primary optical transitions and recombination dynamics in InGaAs self-assembled quantum nanostructures with different shape. Starting from the same quantum dot seeding layer, and depending on the overgrowth conditions, these new nanostructures can be tailored in shape and are characterized by heights lower than 2 nm and base lengths around 100 nm. The geometrical shape strongly influences the electronic and optical properties of these nanostructuctures. We measure for them ground state optical transitions in the range 1.25–1.35 eV and varying energy splitting between their excited states. The temperature dependence of the exciton recombination dynamics is reported focusing on the intermediate temperature regime (before thermal escape begins to be important). In this range, an important increase of the effective photoluminescence decay time is observed and attributed to the state filling and exciton thermalization between excited and ground states. A rate equation model is also developed reproducing quite well the observed exciton dynamics.