Type II photoluminescence and conduction band offsets of GaAsSb/InGaAs and GaAsSb/InP heterostructures grown by metalorganic vapor phase epitaxy

Abstract

The optical properties of lattice-matched GaAsSb/InGaAs/InP heterostructures with a varying InGaAs layer thickness (0–900 Å) were investigated. These structures display strong low temperature type II luminescence, the energy of which varies with the InGaAs layer thickness and ranges from 0.453 to 0.63 eV. The type II luminescence was used to determine directly and accurately the conduction band offset of these structures. The values obtained herein are 0.36 and 0.18 eV at 4.2 K for the GaAsSb/InGaAs and GaAsSb/InP heterojunctions, respectively, with the GaAsSb conduction band higher in energy.

Optical properties and band bending of InGaAs/GaAsBi/InGaAs type-II quantum well grown by gas source molecular beam epitaxy

“…We believe that the underlying mechanism of the observations results from the band bending effect, which is intrinsic for the type-II band alignment of In 0.2 Ga 0.8 As/ GaAs 0.96 Bi 0.04 heterojunction, similar to the cases of GaAs/ GaAsSb 19 and InGaAs/GaAsSb. 27 It is commonly accepted that the band-bending effect is caused by the spatial separation of the photo-excited or electrically pumped carriers in a type-II QW, in which the type-II transition energy is expected to increase proportionally with the third root of the excitation density due to the steepness raising of a triangular-like confining potential. 19 For the In 0.2 Ga 0.8 As/ GaAsBi type-II QW, electrons are confined in the InGaAs layer, and holes are localized in the GaAsBi layer.…”

Self‐assembled silicon‐germanium nanostructures for CMOS compatible light emitters

“…3 Carrier recombination In discussing carrier recombination in Si/SiGe NSs, we focus on MBE and CVD grown samples with an average Ge atomic composition ~50%. These samples show the highest observed PL quantum efficiency with a PL peak wavelength close to 1.5-1.6 m. The PL spectral distribution extending well below the bandgap of pure Ge and the extremely long carrier radiative lifetime of ~10 ms [11], as well as the ~30 meV per decade PL spectral shift toward higher photon energies as the excitation intensity increases, point out strong similarities between the PL in 3D Si/SiGe NSs and the PL in III-V quantum wells with type II energy band alignment [15]. Generally, a type II energy band alignment at the heterointerface is a strong disadvantage for light emitting devices due to a weak overlap between spatially separated electron and hole wave functions.…”

Recombination dynamics of type-II excitons in (Ga,In)As/GaAs/Ga(As,Sb) heterostructures

“…The band-discontinuity between (Ga,In)As and Ga(As,Sb), however, is of type-II. [10,15] After relaxation, the energetically most favorable states for the electrons are in the conduction band (CB) of the (Ga,In)As well and for the holes the Ga(As,Sb) well. From this picture one would expect to see a dominant type-II luminescence between electrons in the (Ga,In)As and the holes in the Ga(As,Sb).…”