Growth temperature effects on boron incorporation and optical properties of BGaAs/GaAs grown by MOCVD

Structural and optical studies of BxGa1−xAs epilayers, grown by metal organic chemical vapor deposition (MOCVD), at different growth temperatures (580 °C and 500 °C), have been achieved by high-resolution X-ray diffraction (HRXRD) and photoluminescence spectroscopy (PL). They have shown that the boron content increases up to 8% with decreasing growth temperature. Low temperature (10 K) PL study has shown an asymmetric broad PL band around 1.34 eV, and a decrease of the intensity with increasing boron composition. The evolution of the emission energy versus temperature can be described by the Varshni law for the high temperature range, while a relative discrepancy has been found to occur at low temperature. Moreover, depending on the temperature range, the PL intensity quenching is found to be thermally ensured by three activation energies for the smallest boron composition (xb ≈ 3%) and by two for the highest (xb ≈ 8%) one. These results are attributed to the localized states induced by the non-uniform insertion and the clustering of the boron atom in BGaAs bulk.