Abstract
This work investigates the effect of the thickness of the epitaxial layer (100 nm and 1 μm) on the optical properties of quaternary GaAs0.1P0.89N0.01 alloys. Furthermore, the effect of rapid thermal annealing (RTA) on their properties has been studied using the Photoluminescence (PL) technique. Increasing the thickness of the epilayer led to an enhancement of the PL intensity as well as the energy bandgap, which was shifted to higher energy (from 1.82 eV in 100 nm to 1.94 eV in 1 μm layer). However, the 1.94 eV bandgap energy is not ideal for solar cells based materials grown on GaP substrates. Post-growth thermal annealing by rapid thermal annealing (RTA) for both samples resulted in an enhancement in the optical properties as observed by a decrease of the Full Width at Half Maximum (FWHM) and an increase of the PL intensity. Therefore, all results obtained in this study indicate that GaAs0.1P0.89N0.01 with 100 nm epilayer thick is better choice to fabricate good efficiency solar cells based materials on GaP substrates as compared to 1 μm sample.
•PL investigation of the effect of thickness and thermal annealing on the optical properties of GaAs0.1P0.89N0.01 alloys.•Increasing the GaAs0.1P0.89N0.01 epilayer thickness leads to an enhancement of the PL intensity and the energy bandgap.•RTA improves the optical properties of both thin and thick as-grown GaAs0.1P0.89N0.01 epilayers but PL energy blue shifts.•PL blue shift after RTA is assigned to a decrease of point defects and localized states radiative effects.•Observation of S-shaped bandgap energy in as-grown and annealed 1 μm thick GaAs0.1P0.89N0.01 due to N localization effect.