Investigating above-bandgap and below-bandgap optical transition in GaBiAs epilayers by photoreflectance spectroscopy

Authors

ÖMER DÖNMEZ
AYŞE EROL

Abstract

We present optical identification of deep level defects in as-grown and annealed GaBixAs$_{1-x}$ (x $=$ 0, 0.013 and 0.015) alloys grown at different temperatures (220 \textdegree C and 320 \textdegree C) by using photo-modulated reflectance (PR) spectroscopy and photoluminescence (PL). The PR measurements are employed at above- and below-bandgap excitations, and the PR line-shape is analyzed by the third derivative functional form (TDFF). The PR at below-bandgap excitation reveals transitions at 0.757 \textpm 0.001 eV and 0.710 \textpm 0.002 eV at 30K and 300K, respectively. Franz-Keldysh oscillations are observed in all samples under above-bandgap excitation at PR measurements, and the built-in electric field, which may originate from the charged As-antisite defects is calculated from local extrema points in the PR spectra. The decrease in the built-in electric field after thermal annealing is explained with decreased point defect density.

DOI

10.3906/fiz-2003-17

Keywords

Dilute bismide alloys, GaBiAs, deep level defect, antisite defect, photoreflectance

First Page

384

Last Page

393

Recommended Citation

DÖNMEZ, ÖMER and EROL, AYŞE (2020) "Investigating above-bandgap and below-bandgap optical transition in GaBiAs epilayers by photoreflectance spectroscopy," Turkish Journal of Physics: Vol. 44: No. 4, Article 6. https://doi.org/10.3906/fiz-2003-17
Available at: https://journals.tubitak.gov.tr/physics/vol44/iss4/6