Energy relaxation at THz frequencies in Al<sub>x</sub>Ga<sub>1-x</sub>As heterostructures
N G Asmar; A G Markelz; E G Gwinn; P F Hopkins; A C Gossard; N G Asmar; Dept. of Phys., California Univ., Santa Barbara, CA, USA; A G Markelz; Dept. of Phys., California Univ., Santa Barbara, CA, USA; E G Gwinn; Dept. of Phys., California Univ., Santa Barbara, CA, USA; P F Hopkins; Dept. of Phys., California Univ., Santa Barbara, CA, USA; A C Gossard; Dept. of Phys., California Univ., Santa Barbara, CA, USA
Журнал:
Semiconductor Science and Technology
Дата:
1994-05-01
Аннотация:
We report 4.2 K studies of the dependence of the in-plane, DC conductivity of a quasi 2D electron gas on the amplitude E<sub>omega </sub> of applied fields with frequencies from 0.25 THz to 3.5 THz. We analyse the dependence of sigma <sub>DC</sub> on E<sub>omega </sub> assuming that electron-optical phonon scattering dominates energy relaxation, that the absorbed power has a Drude form and that the electron distribution is thermal. This simple analysis is self-consistent: Arrhenius plots of the estimated energy loss rate have a slope near -h omega <sub>LO</sub>/k<sub>8</sub>, for all frequencies, as expected for energy loss by optical phonon emission. We find that the effective energy relaxation time tau <sub>epsilon </sub> varies with the frequency of the applied field, from tau <sub>epsilon </sub> approximately 4 ps at 0.34 THz to tau <sub>epsilon </sub> approximately 0.3 ps at 3.45 THz. This may indicate a frequency-dependent form for the hot-phonon distribution.
217.2Кб