Abstract

We used photoluminescence excitation (PLE) spectroscopy at 2K to resolve the spectrum of CdTe quantum dots of different sizes inside their much broader size distribution in CdTe-doped glasses. The spectra obtained show several well-resolved lines, which were only suggested by the usual absorption spectra.¹ We were able to study the confinement as a function of the quantum-dot size with only one sample, just by changing the energy used to collect the photoluminescence. The spectra of different samples collected at the same energy are similar except for the linewidths, which are broader for the samples with larger average quantum-dot size, whereas spectra collected at different energies for the same sample are blue shifted as collection energy increases. The simple model of a particle in a spherical box can explain most of the observed transition lines, except for the second one, which we assigned to the 1S_e-1P_hh forbidden transition. This indicates that a more realistic model should consider hole-band mixing.

© 1994 Optical Society of America