Cathodoluminescence imaging and spectroscopy of excited states in InAs self-assembled quantum dots
- Department of Physics, Ilse Katz Center for Meso and Nanoscale Science and Technology, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)
We have examined state filling and thermal activation of carriers in buried InAs self-assembled quantum dots (SAQDs) with excitation-dependent cathodoluminescence (CL) imaging and spectroscopy. The InAs SAQDs were formed during molecular-beam epitaxial growth of InAs on undoped planar GaAs (001). The intensities of the ground- and excited-state transitions were analyzed as a function of temperature and excitation density to study the thermal activation and reemission of carriers. The thermal activation energies associated with the thermal quenching of the luminescence were measured for ground- and excited-state transitions of the SAQDs, as a function of excitation density. By comparing these activation energies with the ground- and excited-state transition energies, we have considered various processes that describe the reemission of carriers. Thermal quenching of the intensity of the QD ground- and first excited-state transitions at low excitations in the {approx}230-300-K temperature range is attributed to dissociation of excitons from the QD states into the InAs wetting layer. At high excitations, much lower activation energies of the ground and excited states are obtained, suggesting that thermal reemission of single holes from QD states into the GaAs matrix is responsible for the observed temperature dependence of the QD luminescence in the {approx}230-300-K temperature range. The dependence of the CL intensity of the ground-and first excited-state transition on excitation density was shown to be linear at all temperatures at low-excitation density. This result can be understood by considering that carriers escape and are recaptured as excitons or correlated electron-hole pairs. At sufficiently high excitations, state-filling and spatial smearing effects are observed together with a sublinear dependence of the CL intensity on excitation. Successive filling of the ground and excited states in adjacent groups of QDs that possess different size distributions is assumed to be the cause of the spatial smearing.
- OSTI ID:
- 20711754
- Journal Information:
- Journal of Applied Physics, Vol. 97, Issue 12; Other Information: DOI: 10.1063/1.1935743; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
Similar Records
Detection of the Third Transition of InAs/GaAsSb Quantum Dots
Role of Atomic Structure on Exciton Dynamics and Photoluminescence in NIR Emissive InAs/InP/ZnSe Quantum Dots
Related Subjects
ACTIVATION ENERGY
CATHODOLUMINESCENCE
CRYSTAL GROWTH
DISSOCIATION
ELECTRON CORRELATION
EXCITATION
EXCITED STATES
EXCITONS
GALLIUM ARSENIDES
GROUND STATES
HOLES
INDIUM ARSENIDES
LAYERS
MOLECULAR BEAM EPITAXY
QUANTUM DOTS
SEMICONDUCTOR MATERIALS
SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K