Molecular beam epitaxy of AlGaAsSb system for 1.55 mu m Bragg mirrors

The growth of AlGaAsSb materials on InP substrate was carried out by elemental source molecular beam epitaxy (MBE). The control of group-V composition appeared complex. In order to minimize the fluctuations of group-V composition, its dependence on growth temperature, cracking of the group-V species, growth rate and Al/Ga ratio were evaluated. Then we focused on AlAsxSb1-x and AlzGa1-zAsySb1-y alloys with x and y allowing lattice matching to InP, and with z around 0.10 in order to have transparency at 1.55 mu m. Pairing these alloys, we built up Bragg mirrors with the reflectivity centered at 1.55 mu m. A mirror consisting of 20 1/2 pairs exhibited a reflectivity of 99.8% with a 200 nm stopband width. Doping studies of these materials demonstrated n- and p-type conductivities with carrier concentrations over 10(-19) cm(-3) where Te and Be were, respectively, the n- and p-type dopants.