Ultrafast electron trapping times in low-temperature-grown gallium arsenide: The effect of the arsenic precipitate spacing and size

The role and interplay of basic structure parameters of arsenic precipitate s on the ultrafast trapping of conduction band electrons has been studied i n a series of low-temperature-grown GaAs epilayers grown at various tempera tures ranging from 170 up to 325 degreesC and annealed at 600 degreesC. Cro ss sectional electron-transmission characterization was used to determine t he density and size of the precipitated arsenic clusters with growth temper ature. The dependence of the electron trapping times (tau) on the spacing ( R) and radius (alpha) of the arsenic precipitates has been systematically s tudied by time-resolved pump-probe transient transmission spectroscopy. The present work demonstrates that the electron trapping time follows a tau pr oportional toR(3)/alpha law. (C) 2001 American Institute of Physics.