LATERAL AND CROSS-WELL TRANSPORT OF HIGHLY AND MODERATELY EXCITED CARRIERS IN SI1-XGEX SI SUPERLATTICES/

Picosecond transient reflectometry and dynamic grating techniques have been applied to investigate the perpendicular and parallel transport of optically excited carriers in strained-layer Si0.83Ge0.17/Si superl attices. We present results of the carrier ambipolar diffusivity and e ffective lifetime measurements in the layered structure and substrate within the 10(17)-10(20) cm(-3) density range. The combined experiment al data are discussed in terms of parallel and perpendicular diffusion of carriers, interface recombination, and lattice heating. The estima ted lateral and cross-well diffusion constants are 10 and 0.16 cm(2)/s at room temperature, respectively. (C) 1998 American Institute of Phy sics.