Frequency-dependent complex conductivity of high-mobility GaAs and InAs two-dimensional-electron-gas (2DEG) systems is studied by terahertz time domain spectroscopy. Determining the momentum relaxation time from a Drude model, the authors find a lower value than that from dc measurements, particularly at high frequencies/low temperatures. These deviations are consistent with the ratio tau(t)/tau(q,) where tau(q) is the full scattering time. This suggests that small-angle scattering leads to weaker heating of 2DEGs at low temperatures than expected from dc mobilit9y. (c) 2006 American Institute of Physics.

10afield-effect transistors10aphotoconductivity10aPhysics10aplasma-waves10aradiation10aresonant detection10asubterahertz1 aKabir, N., A.1 aYoon, Y.1 aKnab, J., R.1 aChen, J., Y.1 aMarkelz, A., G.1 aReno, J., L.1 aSadofyev, Y.1 aJohnson, S.1 aZhang, Y., H.1 aBird, J., P. uhttp://markelz.physics.buffalo.edu/node/229