Time-Resolved Depletion Region Carrier Dynamics at Semiconductor Surfaces & Interfaces

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Recently we performed a time-resolved experiment which clearly demonstrates the effect of the surface space-charge field on the depletion region carrier dynamics in GaAs. These studies can potentially yield considerable insight into carrier transport properties near semiconductor surfaces and buried semiconductor interfaces, and in submicron devices, where the surface space-charge field spans most, if not all, of the semiconductor device structure. We propose several important new extensions of our experimental studies. First, we propose to enhance our current measurement technique by utilizing variable wavelength probe pulses. This will permit us to vary our information depth within the surface space-charge region in our experiments, facilitating a more quantitative theoretical model of the depletion region carrier transport. Second, we would like to extend our measurements to include other systems, such as silicon device structures, GaAs/ZnSe buried interfaces, and semiconductor/ metal interfaces. Third, we would like to extend our measurements into the variable pump intensity regime, enabling us to include photomodulation effects of the surface or interface space-charge field. These measurements will provide a detailed picture of the dynamics of the screening process at a semiconductor surface or interface, enabling us to analyze structures with inhomogeneous dopant densities directly adjacent to an interface.