Exciton relaxation dynamics in ultrathin CdSe/ZnSe single quantum wells

• Published in: Journal of crystal growth 1994-04, Vol.138 (1), p.849-855
• Main Authors: Neukirch, U., Weckendrup, D., Faschinger, W., Juza, P., Sitter, H.
• Format: Article
• Language: English
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Collective excitations (including plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Ii-vi semiconductors; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoluminescence; Physics; Surface and interface electron states
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/0022-0248(94)90919-9

Ultrathin CdSe/ZnSe single quantum wells grown by self-limiting monolayer epitaxy are investigated by means of time integrated as well as picosecond time-resolved luminescence spectroscopy. Well thicknesses are 1, 2 and 3 monolayers of CdSe. All samples exhibit a bright excitonic luminescence which shows, for an SQW of one monolayer thickness, a blue shift of 850 meV with respect to bulk CdSe. The transient behavior of the luminescence varies depending on energy of detection. At high energies, the decay is very fast and nonexponential. At the low-energy side of the luminescence band, a slower, simply exponential decay is observed. A model of excitons relaxing in a random potential is set up to describe and discuss the experimental data. Under resonant excitation into higher well states, several phonon replica of recombining, resonantly excited excitons occur.