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

Authors

ÖMER DÖNMEZ
AYŞE EROL

DOI

10.3906/fiz-2003-17

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.

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