Publication
Carrier capture into semiconductor quantum dots via quantum wire barriers: Localization and thermionic emission effects
Abstract
Carrier transport and capture paths via barriers of different dimensionality in AlGaAs/GaAs quantum wire (QWR)/quantum dot (QD) heterostructures, grown in inverted pyramids, are studied by photoluminescence (PL) spectroscopy. Evidence for thermally activated diffusion related to potential disorder in the QWR barriers and thermionic emission of carriers from the QD into the QWR barrier is observed in temperature dependent PL spectra. Similar activation energies for the thermionic emission are derived from the continuous-wave and time-resolved PL spectroscopy.
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Related concepts (32)
Thermionic emission
Thermionic emission (also known as thermal electron emission or the Edison effect) is the liberation of electrons from an electrode by virtue of its temperature (releasing of energy supplied by heat). This occurs because the thermal energy given to the charge carrier overcomes the work function of the material. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions. After emission, a charge that is equal in magnitude and opposite in sign to the total charge emitted is initially left behind in the emitting region.
Quantum dot
Quantum dots (QDs) – also called semiconductor nanocrystals, are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from those of larger particles as a result of quantum mechanics. They are a central topic in nanotechnology and materials science. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band.
Field electron emission
Field electron emission, also known as field emission (FE) and electron field emission, is emission of electrons induced by an electrostatic field. The most common context is field emission from a solid surface into a vacuum. However, field emission can take place from solid or liquid surfaces, into a vacuum, a fluid (e.g. air), or any non-conducting or weakly conducting dielectric. The field-induced promotion of electrons from the valence to conduction band of semiconductors (the Zener effect) can also be regarded as a form of field emission.
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