Photoluminescence studies of Mg-doped Al_xGa_1-xAs epitaxial layers grown by molecular beam epitaxy

Magnesium (Mg)-doped Al_xGa_1-xAs epitaxial layers were grown by molecular beam epitaxy (MBE) at various substrate temperatures, Al mole fractions, and As/Ga beam equivalent pressure (BEP) ratios. The optical properties were investigated by photoluminescence (PL) spectroscopy. The PL emission peak intensity was increased and the emission peak was slightly blue shifted from 700.7 to 697.3nm when the substrate temperature was increased. The full width at half maximum (FWHM) was decreased from 29.6 to 19meV when the substrate temperature was increased. The other growth parameters, such as the As/Ga BEP ratio and the Al mole fraction, also affected the optical properties of the Mg-doped Al_xGa_1-xAs epilayers. The anomalous behavior of the blue- and red-shift of the PL peak energy was observed also to be temperature dependent.