Ultrafast carrier dynamics in InGaAsP grown by He-plasma-assisted epitaxy

We perform dual-wavelength pump-probe measurements on InGaAsP grown by Ile- plasma-assisted molecular beam epitaxy with Be doping concentrations rangin g from 0 to 6 x 10(18) cm(-3). The material response times obtained vary fr om 1 to >70 ps depending on doping concentration, pump pulse energy, and pr obe wavelength. A two-trap-level rate equation model is presented to explai n the various response times observed, and trap densities of 2.5 x 10(17) a nd 12 x 10(17) cm-3, electron-capture cross-sections of 12 x 10(-15) and 2. 8 x 10(-15) cm(2), and hole-capture cross-sections of 1.4 x 10(-16) and 1.8 x 10(-15) cm(2) are derived by fitting the experimental data. Dual-pulse p ump-probe measurements indicate that a fast repeated switching on a similar to 10 ps timescale using Be-doped materials can be achieved despite the sl ow hole-capture rate associated with one of the trap levels. (C) 2000 Publi shed by Elsevier Science B.V.