Few-electron ground states of charge-tunable self-assembled quantum dots

Directed self‐assembly of single quantum dots for telecommunication wavelength optical devices

“…Ideally, one would like to control the exciton charge state on an individual quantum dot. This can be accomplished utilizing metal-oxide-semiconductor or metal-semiconductor structures whereby tunneling of the electrons in and out of the quantum dot is achieved via electric fields [42,[57][58][59][60][61][62]. A single quantum dot in a pyramidal nanotemplate forms an ideal geometry for devices requiring metal gates for application of electric fields and optical access for PL spectroscopy.…”

Coulomb-Interaction-Induced Incomplete Shell Filling in the Hole System of InAs Quantum Dots

“…Up until the present, mainly conduction band states have been studied in this context where capacitance-voltage (C-V) spectroscopy provided valuable information on the level structure and the Coulomb interactions 4,5,6 . A non-sequential level filling for degenerate or nearly degenerate, respectively, energy levels, i. e., the manifestation of Hund´s first rule, was observed in some experiments on self-assembled InAs QDs 7 .…”

Multiple charging ofInAs∕GaAsquantum dots by electrons or holes: Addition energies and ground-state configurations

“…Actually there are some experimental evidences showing that the ground state of 4 electrons could be a low spin state. 6,46 In contrast to electrons, holes have ∆ǫ h ≤ J ss , and large p 1 -p 2 splitting, small p 2 -d 1 splitting (Fig. 2), which place the holes in a different region in the phase diagrams than electrons, where there are more competing phases.…”

“…The addition energies are summarized in Table V. Experimentally, the charging energies of electrons 4,5,6 and holes 11,13 in self-assembled QDs are usually measured via capacitance spectroscopy, using gated structures. 48 The (In,Ga)As/GaAs dots used in the electron charging experiments were roughly estimated to be 7 nm in height and 20 nm in base in Refs.…”

“…This is afforded either by injecting from a tip of a scanning tunneling microscope, 1 or by various gate structures. 2,3,4,5,6,7,8,9,10,11 Since the energy scale of both single-particle levels and Coulomb interactions in quantum dots (QDs) (10 −4 -10 −2 Ry) are a few order of magnitudes smaller than those of the real atoms ( ∼ 1 Ry), dots can be loaded by as many as six 4 to ten 12 electrons in colloidal 12 and self-assembled 4,8,9 dots having confining dimension of ≤ 50Å, and up to hundreds of electrons in larger 500Å electrostatically confined dots. 2,3,7 The "charging energy" µ(N ) is the energy needed to add a carrier to the dot that is already loaded by N − 1 carriers,…”