Classification of Energy Levels in Quantum Dot Structures by Depleted Layer Spectroscopy |
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Authors: | M Kaniewska O Engström M Kaczmarczyk |
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Affiliation: | (1) Department of Physics, North Carolina State University, Raleigh, NC 27695–8202, USA |
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Abstract: | The coexistence of quantum confined energy levels and defect energy levels in quantum dot (QD) structures may cause difficulties
in distinguishing between their different origin when using deep-level transient spectroscopy (DLTS). Using InAs/GaAs QDs
as demonstration vehicles, we present methodologies to obtain such a classification by DLTS. QD-related spectra measured as
a function of repetition frequency of electrical pulses, f, or temperature, T, and reverse voltage, V
R, are depicted as contour plots on (f, V
R) and (T, V
R) planes, thus reflecting the complex thermal and tunneling emission of electrons from the ground and excited states. Defect-related
levels give rise to different contour patterns and undergo modification, exhibiting double-peak structured emission when defects
are agglomerated in the vicinity of the QD plane. This effect is interpreted in terms of an interaction between electron states
in traps and the confined QD states. |
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Keywords: | |
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