Classification of Energy Levels in Quantum Dot Structures by Depleted Layer Spectroscopy

• 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.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Annan teknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Other Engineering and Technologies (hsv//eng)

Nyckelord

deep-level transient spectroscopy

GAAS/GAAS

structures

defect energy levels

TRANSIENT SPECTROSCOPY

quantum dot

GROWTH TECHNIQUE

Quantum confined energy levels

STATES

DEEP LEVELS

ELECTRON TRAPS

HETEROSTRUCTURES

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