Subpicosecond carrier lifetime in beryllium-doped lnGaAsP grown by He-plasma-assisted molecular beam epitaxy

The carrier dynamics and absorption edges of InGaAsP samples grown by He-plasma-assisted molecular beam epitaxy and doped with various concentrations of beryllium are investigated via pump-probe experiments and Fourier transform infrared (FTIR) absorption spectroscopy. Carrier lifetimes from 10 to <1 ps are obtained for samples of increasing doping concentrations. The reduced in carrier lifetimes are attributed to Be compensation of the deep donor levels introduced by the He plasma. The carrier lifetime increases with photogenerated carrier density due to trap saturation. The FTIR results reveal sharp absorption edges in this material for doping concentrations up to 1×1018 cm−3. The fast carrier dynamics and the steep absorption edge make this material very attractive for ultrafast optical switching devices for use in high-speed time-division-multiplexing fiber communication systems.