Optical investigation of highly strained InGaAs-GaAs multiple quantum wells

Abstract

Low-temperature optical transmission spectra of several InxGa1−xAs/GaAs strained multiple quantum wells (MQWs) with different well widths and In mole fractions have been measured. The excitonic transitions up to 3C-3H are observed. The notation nc-mH(L) is used to indicate the transitions related to the nth conduction and mth valence heavy (light) hole subbands. Steplike structures corresponding to band-to-band transitions are also observed, which are identified as 1C-1L transitions. The calculated transition energies, taking into account both the strain and the quantum well effects, are in good agreement with the measured values. In these calculations the lattice mismatch between the GaAs buffer and the InGaAs/GaAs MQW is taken into account and the valence-band offset Qv is chosen as an adjustable parameter. By fitting the experimental results to our calculations, we conclude that the light holes are in GaAs barrier region (type II MQW) and the valence-band offset Qv is determined to be 0.30. A possible system in which the transition from type I to type II for light holes might be observed is also discussed.

InGaAs spin light emitting diodes measured in the Faraday and oblique Hanle geometries

“…This may explain the negative polarization peak seen at higher energy. However, it would be expected that the light-hole peak was separated by around 50 meV from the heavy-hole peak [24], rather than the 10 meV seen here. In figure 4 the quantity S 0Y· T s /τ R is plotted on the lefthand axis versus temperature, where S 0Y· T s /τ R is the optical polarization of the electrons in the quantum well.…”

Influence of growth direction and strain conditions on the band lineup at GaSb/InSb and InAs/InSb interfaces

“…Only recently, an InSb quantum-well has been realized in GaSb [2]; starting from photoluminescence peak emission energy data and from calculations based on a standard finite square-well model [26,27] (taking into account strain [28,29]), a VBO of 0.16 eV was obtained that is quite different from the one, 0.34 eV, reported in Table II.…”

Band anticrossing effects in highly mismatched semiconductor alloys

“…tensile strain introduced by this small mismatch may raise the valence band of GaAs 1-x N x by 40 meV at most [63]. The quantum confinement of the holes by this shallow well has been estimated to decrease the transition energies by less than 20 meV for all the QW's studied here.…”