Giant permanent dipole moments of excitons in semiconductor nanostructures

Department of Physics, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom Center for NanoScience and Sektion Physik, Ludwig-Maximilians-Universita ̈t, Geschwister-Scholl-Platz 1, D-80539 München, Germany Instituto de Microelectronica de Madrid, CNM-CSIC Isaac Newton, 8, PTM, 28760 Madrid, Spain Materials Department and QUEST, University of California, Santa Barbara, California 93106 ~Received 20 June 2001; published 15 February 2002 !