Proposal Number: ECS-9528854 Principal Investigator: Arthur L. Smirl "Ultrafast carrier transport, screening and space-charge field formation in semiconductors" ABSTRACT Comprehensive studies of carrier dynamics and space-charge formation in semiconductor structures will be performed. Future photonic and electronics systems, and interconnects between the two, will rely on and be limited by the ability to control carrier transport over micron and nanometer sized dimensions and by an understanding of the space-charge formation, screening and changes in optical properties that accompany such transport. Five interrelated research tasks will form the main body of the research (1) measurement of time-resolved Stokes parameters for the four-wave mixing signal to study exciton-exciton interactions and carrier scattering in multiple quantum wells; (2) development of sensitive new techniques to measure coherent plasma oscillations which results from ballistic transport. These measurements are expected to provide information about transport/scattering processes which cannot be obtained in any other way; (3) measurement of the per volt electro-optic and per carrier nonlinear optical responses of "stacked SEEDs" electro-optic modulator structures; (4) investigation of the transport, screening and electro-optic response of strained piezo-electric multiple quantum wells; and (5) use of ultrafast techniques to measure/quantify the dynamics of photogenerated carriers, space-charge field formation and the tunneling times in optically switched resonant tunneling diodes.
