Dresden 2006 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 10: Electric, Electromechanical and Optical Properties I
DF 10.5: Vortrag
Donnerstag, 30. März 2006, 16:10–16:30, M{\"U}L Elch
Space-charge waves in silicon carbide — •M. Lemmer1, M. Imlau1, M. Petrov2, V. Bryksin2, and A. Lebedev2 — 1Department of Physics, University of Osnabrück — 2Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg
The non-linear phenomenon of space-charge waves (SCW) is investigated in single crystals of 4H-SiC polytype. By excitation with an oscillating interference pattern at λ = 488 nm and an externally applied electric field of 0 < E0 ≤ 10 kV/cm spatial rectification (SR) is found. The amplitude and the frequency of the SR-resonance signal show relevant dependences on the applied electric field and the wave number K of the interference pattern. For instance the amplitude exhibits a pronounced maximum at low values of K of approximately 2 · 103 cm−1. All results are successfully described by the generalized SCW-model, if the effect of trap saturation, caused by a limited trap density, is considered. This allows to determine important material parameters of 4H-SiC like the product of mobility and lifetime of the charge carriers µ τ = (7.4 ± 0.8) · 10−7 cm2/V, the Maxwell relaxation time τM = (5.3 ± 0.6) · 10−4 s, and the effective trap concentration Neff = (5 ± 1) · 1013 cm−3.
Supported by the Deutsche Forschungsgemeinschaft (DFG, projects GRK 695 and 436 RUS 17/16/06).