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

Authors : Ömer DÖNMEZ, Ayşe EROL

Pages : 384-393

View : 18 | Download : 13

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :We present optical identification of deep level defects in as-grown and annealed GaBixAs1−xinsert ignore into journalissuearticles values(x=0, 0.013 and 0.015); alloys grown at different temperatures insert ignore into journalissuearticles values(220 °C and 320 °C); by using photo-modulated reflectance insert ignore into journalissuearticles values(PR); spectroscopy and photoluminescence insert ignore into journalissuearticles values(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 insert ignore into journalissuearticles values(TDFF);. The PR at below-bandgap excitation reveals transitions at 0.757 ±0.001 eV and 0.710 ±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