Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 40: THz and MIR Physics in Semiconductors
HL 40.4: Vortrag
Freitag, 9. September 2022, 10:15–10:30, H33
Highly superlinear terahertz photoconductance in GaAs quantum point contacts in the deep tunneling regime — •Maximilian Otteneder1, Marcel Hild1, Ze-Don Kvon2,3, Ekaterina E. Rodyakina2,3, Mikhail M. Glazov4, and Sergey D. Ganichev1,5 — 1Terahertz Center, University of Regensburg, Regensburg, Germany — 2Novosibirsk, Russia — 3Novosibirsk, Russia — 4St. Petersburg, Russia — 5CENTERA, Institute of High Pressure Physics, Warsaw, Poland
A highly superlinear in radiation intensity photoconductance induced by continuous wave terahertz laser radiation with low intensities has been observed in quantum point contacts made of GaAs quantum wells operating in the deep tunneling regime. For very low values of the dark conductance Gdark/G0≈ 10−6, with the conductance quantum G0=2e2/h, the photoconductance scales exponentially with radiation intensity and increases by almost four orders of magnitude at already 100 mW/cm2. This effect is observed for a radiation electric field oriented along the source drain direction. We provide model considerations of the effect and attribute it to the variation of the tunneling barrier height by the radiation field due to local diffraction effects. We also demonstrate that cyclotron resonance due to an external magnetic field manifests itself in the photoconductance, completely suppressing the photoresponse.