Limits of semiclassical transport in narrow miniband GaAs/AlAs superlattices

The luminescence properties of highly strained, Sb-doped Ge/Si multi-layer heterostructures with incorporated Ge quantum dots (QDs) are studied. Calculations of the electronic band structure and luminescence measurements prove the existence of an electron miniband within the columns of the QDs. Miniband formation results in a conversion of the indirect to a quasi-direct excitons takes place. The optical transitions between electron states within the miniband and hole states within QDs are responsible for an intense luminescence in the 1.4-1.8 lm range, which is maintained up to room temperature. At 300 K, a light emitting diode based on such Ge/Si QD superlattices demonstrates an external quantum efficiency of 0.04% at a wavelength of 1.55 lm.

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“…The existence of true miniband conduction via interface roughness scattering was highlighted by the authors of Ref. [93].…”

Section: Temporal Profile Of Qdsl Plmentioning

confidence: 97%

“…The authors of Ref. [93] observed miniband transport between~77 K and 400 K in GaAs/AlAs superlattices.…”

Section: Temporal Profile Of Qdsl Plmentioning

confidence: 98%

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

et al. 2006

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“…We followed the usual Monte Carlo scheme, described in Ref. [3], which consists of modeling the motion of an electron as a sequence of free flights interrupted by collisions. The duration of each flight, the scattering mechanism operating at the end of the flight, and the quantum state of the electron after the instantaneous scattering process, were chosen stochastically using a random number generator.…”

Section: Modelmentioning

confidence: 99%

“…A more complete description, however, requires the inclusion of multiple scattering processes, with a complicated dependence of the scattering amplitude on sample parameters and external fields. In such a case, Monte Carlo simulations have been used to model the conductivity for various type-I band alignment systems [3,4], which produces a semiclassical description in which Wannier-Stark quantization [5] is not included.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo studies of miniband conduction in extreme type-II superlattices

2004

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Miniband charge transport was investigated by Monte Carlo simulations of electronic motion in short period superlattices of type-II energy band alignment (InAs/GaSb composition). The strong decrease of the miniband energy width when the electronic in-plane energy increases, characteristic of type-II superlattices, leads to a conductivity that is very sensitive to a magnetic field applied parallel to the axis of the superlattice. For structures with a miniband energy width greater than the optic phonon energy, the differential conductance can be changed from positive to negative by the magnetic field, due to the suppression of optic phonon emission.

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“…In particular, electron negative differential velocity (NDV) has been proved in superlattice unipolar diodes whose static characteristics exhibit negative differential conductance (NDC) [6,7,9]. The effect is adequately described by miniband transport models relying upon the Boltzmann equation or balance equations [13,16].…”

Section: Introductionmentioning

confidence: 99%