Electron wave-function spillover in self-assembledInAs∕InPquantum wires

Abstract

Charge confinement in InAs/ InP self-assembled quantum wires is studied experimentally using photoluminescence in pulsed magnetic fields and theoretically using adiabatic theory within the effective-mass approximation, taking into account the strain in the samples. We show both experimentally and theoretically that, in spite of the large conduction band offset, the electron wave function is significantly spilled out of the wire in the wire height direction for thin wires. Furthermore, for a wire thickness of up to 8 monolayers, the electron spillover is inversely related to the wire height. These effects are due to the large zero point energy of the electron. As the wire becomes thicker, the decrease in confinement energy is reflected in a reduction of the electron wave-function extent.

Optical observation of single-carrier charging in type-II quantum ring ensembles

“…Recombination from excited hole states 11 and light-hole states are likely to be present in the measured PL, but not resolved. A second possible explanation for the sub-peaks is monolayer fluctuations 18 in the size of the rings. If this were the case, the lower energy emission from larger structures would be expected to saturate at higher powers than the higher energy emission from smaller structures.…”

Different regimes of electronic coupling and their influence on exciton recombination in vertically stacked InAs/InP quantum wires

“…In order to discuss the PL results in terms of each component, we have performed a multi-Gaussian fit to the PL spectra, as plotted by dotted lines in figure 2. The Gaussian-components P1-P4 are associated to exciton recombination at four different QWR families of different average heights, being approximately 1 ML the height fluctuation between two of such consecutive families, as demonstrated in previous work [19,25]. The Gaussian labelled as P5 is not experimentally well resolved within the PL band.…”

“…The average height of the QWR families responsible for the P1-P2-P3-P4 PL components are approximately 5-6-7-8 ML (1.5-2.5 nm), by comparing their peak energies with calculations of two previous works using, respectively, the kp and adiabatic theory with the following conditions: effectivemass approximation, assuming rectangular QWRs and taking into account the strain in the sample [19,25]. When reducing the InP spacer thickness we observe how the lower energy PL components (P3-P4) exhibit an increase in intensity, as shown in figure 2.…”

Mobility asymmetry in InGaAs/InAlAs heterostructures with InAs quantum wires

“…Because of the elongated structure, the electron energy in the quantum wires, unlike quantum dots, is quasi-continuous above the ground quantized state. Furthermore, because of the smaller barrier in the InAs/InGaAs system (as compared with the conventional InAs/GaAs system), the electrons in the wires are weakly confined [12,13]. The electrons are likely to move around easily and couple together with the 2D electrons in the interface channel.…”