Investigation of the effect of different thicknesses and thermal annealing on the optical properties of GaAs0.1P0.89N0.01 alloys grown on GaP substrates

Abstract

This work investigates the effect of the thickness of the epitaxial layer (100nm and 1μm) 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 100nm to 1.94 eV in 1μm 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 100nm epilayer thick is better choice to fabricate good efficiency solar cells based materials on GaP substrates as compared to 1μm sample.