Areas of Research

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Carrier Dynamics in Solid-State Materials

Fundamental electrical and optical properties of solid-state materials are determined by the dynamical response of charge carriers to external fields. The near-equilibrium carrier properties define carrier transport and optical conductivity. With tools of ultrafast spectroscopy we can now probe the nonequilibrium carrier dynamics on the femtosecond time scale (10 -15 s).

Time-resolved two-photon photoemission (TR-2PP) spectroscopy is a versatile technique for energy and momentum resolved studies of electronic structure and carrier relaxation dynamics in solids. With this technique we are investigating the quantum mechanical phase and carrier population relaxation times in metals, metal oxides, and semimetals, as well as their intrinsic and adsorbate induced surface states. Of particular interest are the physical processes that induce e-h pair decoherence, because they impose limits on time scales for quantum control of carriers through the phase of the excitation light. The manipulation of coherent excitations with light may enable ultrafast (>10 THz) switching and information processing, as well as, atomic manipulation of matter.