Optical study of BxGa1−xAs/GaAs epilayers

Optical studies of BxGa1−xAs/GaAs epilayers grown by Metal Organic Chemical Vapor Deposition (MOCVD), with boron composition ≤ 7%, have been achieved by photoluminescence spectroscopy (PL) as a function of the excitation density and the sample temperature (10–300 K). The Raman scattering have shown a linear variation between boron composition and Raman shift of the optical phonons modes. It has shown that the BGaAs PL band shifts to low energy side when the boron composition is ≤ 2.5% compared to the GaAs one. But this band increases slowly as the boron content increases in range 2.5% to 7%. Blue shifts of the PL bands were observed when increasing the excitation density. The temperature dependence of the PL peak energy has shown an S-shaped behavior. Based on these experimental results, we have suggested that the carrier recombination mechanisms in the BGaAs epilayer result from exciton-localization like mode. These experimental results show that boron incorporation does not cause a great modification of the band structure in BxGa1−xAs alloys compared to the pure GaAs.