Disorder and the Urbach edge in dilute bismide GaAsBi

Abstract

The characteristic emission from tail states below the bandgap of GaAsBi/GaAs quantum wells is studied using photoluminescence spectroscopy over a 10–300 K temperature range and a 0.1–1000 mW pump power range. The tail states exhibit two characteristic energies: A deeper one that is temperature independent at 29 meV and one nearer to bandgap that is temperature dependent, broadening from 17 meV at 10 K–29 meV at room temperature. The tail states are thought to originate from localization of the Bi states and disorder effects due to alloy fluctuations and clustering on the group-V sublattice.

Atomistic tight-binding study of electronic structure and interband optical transitions in GaBixAs1−x/GaAs quantum wells

“…Recent experimental measurements 5,8,9 have revealed a strong band-edge broadening in GaBi x As 1Àx alloys, including a pronounced Urbach tail thought to originate from Bi-related localized states. 9 Simplified continuum methods such as the band-anticrossing (BAC) model 10 fail to capture the alloy fluctuation effects and the associated inhomogeneous broadening of the resonant defect level energies.…”

“…9 Simplified continuum methods such as the band-anticrossing (BAC) model 10 fail to capture the alloy fluctuation effects and the associated inhomogeneous broadening of the resonant defect level energies. Analysis of the inhomogeneous broadening demands atomistic modelling techniques to realistically represent the Bi atom distribution in GaBi x As 1Àx bulk and QW structures.…”

Photoreflectance and photoluminescence study of localization effects in GaAsBi alloys

“…Epitaxial layers of GaAsBi have demonstrated a reduced temperature dependence of the lasing wavelength, which makes them promising for the manufacture of laser diodes and semiconductor optical amplifiers that do not require Peltier cooling [10]. Recently, a large number of reports on detailed optical characterizations of GaAsBi were published [7,14,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. They include temperature dependence of PL, time-resolved PL, Photomodulated transmittance and photoreflectance (PR).…”

Molecular beam epitaxy using bismuth as a constituent in InAs and a surfactant in InAs/InAsSb superlattices

“…In addition to moving the valence band up toward the conduction band, Bi clusters may form which introduce distributions of states near the valence band edge which also give photoluminescence. 6,7 The temperature dependence of the PL peak energy of each sample is fit to an Einstein single oscillator model for temperatures up to 120 K; the respective Einstein temperatures for the reference structure and quantum wells 1 and 2 are 74, 162, and 151 K.…”

“…This phenomenon introduces a distribution of localized states in the vicinity of the valence band. 6,7 This behavior is a unique feature in the electronic band structure of III-V-Bi semiconductors.…”