Photoreflectance and photoluminescence study of annealing effects on GaAsBi layers grown by metalorganic vapor phase epitaxy

Abstract

The optical properties of GaAsBi layers grown by atmospheric pressure metalorganic vapor phase epitaxy on p-type GaAs substrates and annealed at different temperatures are investigated by photoreflectance and photoluminescence spectroscopies. Photoreflectance spectra show no significant shift in the band gap energy of GaAs 0.965 Bi 0.035 with annealing temperature except 600 • C for which the band gap energy reaches a minimum value corresponding to a red shift of 60 meV. The low temperature photoluminescence spectra of GaAsBi layers show a broad band centered at ∼1.36 eV. The temperature dependence of the 1.36 eV emission band in addition to the increasing intensity of this band with bismuth flow suggests that it is originated from Bi clusters or from complex defects probably located at the surface/interface of the GaAsBi epilayer.

Novel Dilute Bismide, Epitaxy, Physical Properties and Device Application

“…There are a number of annealing studies reported and they are summarized in Table 5 below. Most previous reports focus on RTA of GaAsBi grown by both MBE [141,[143][144][145][146][147] and MOCVD [148,149]. The growth temperature used is between 200 and 420 • C measured by a thermocouple.…”

“…Post-growth RTA is performed at 500-900 • C for a typical duration of 30-900 sec. The most common assessment methods are HRXRD and PL, while other methods like time-resolved PL [144,146] and PR [149] are sometime used.…”

“…The XRD pattern shows no change up to 700 • C for 900 s while the 10 K PL reveals an enhancement of integrated PL intensity by more than 10 times and a reduction of FWHM from 126 meV to104 meV. Later, the same group used PR to evaluate transitions in GaAs 0.965 Bi 0.035 and found a red-shift of 60 meV after RTA at 600 • C for 900 s [149]. No change in XRD is observed while the 10 K PL shows a peak at a constant energy of 1.36 eV when increasing the annealing temperature to 600 • C. This anomalous red-shift measured by PR is unexpected and the authors attribute it to an internal rearrangement of Bi atoms inside GaAsBi.…”

“…By comparing the reduced effective mass and exciton radius of each PL process, they clarified that the interface of GaSbBi/AlGaSb QW is a terrace-like structure, due to the Bi-induced interfacial Al/Ga inter-diffusion. [20,21,25,29,44,74,149,161,165,168,185,188,190,205,212,[235][236][237].…”

Effects of Thermal Annealing on the Spectral Properties of GaAsBi Alloys Grown by Molecular Beam Epitaxy (MBE)

“…Chine et al have studied the effects of annealing on the photo-reflectance and photoluminescence for GaAsBi layers grown by metal-organic vapor phase epitaxy [9]. They reported that PL measurements below 100 K show a new large band centered at 1.36 eV and depends strongly on bismuth flow.…”