Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 12: HL Poster I

HL 12.43: Poster

Montag, 1. April 2019, 17:30–20:00, Poster E

Sign-alternating photoconductivity and magnetoresistance oscillations induced by terahertz radiation in HgTe quantum wells — •Maximilian Otteneder¹, Ivan Dmitriev^1,2, Susanne Candussio¹, Maxim Savchenko³, Dmitry Kozlov³, Vasily Bel’kov², Ze-Don Kvon³, Nikolay Mikhailov³, Sergey Dvoretsky³, and Sergey Ganichev¹ — ¹University of Regensburg, Regensburg, Germany — ²Ioffe Institute, St. Petersburg, Russia — ³Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia

We report on the observation of terahertz radiation induced photoconductivity and of terahertz analog of the microwave-induced resistance oscillations (MIRO) in HgTe quantum wells (QWs). The MIRO-like effect has been detected in 20 nm QWs with a mobility of 3 × 10⁵ cm²/V s. In other structures with QW widths ranging from 5 to 20 nm and lower mobility we observed an unconventional non-oscillatory photoconductivity signal which changes its sign upon magnetic field increase. In samples having Hall bar and Corbino geometries this results in a single and double change of the photoresponse sign, respectively. We show that within the bolometric mechanism these unusual features imply a non-monotonic behavior of the transport scattering rate, which should decrease (increase) with temperature for magnetic fields below (above) a certain value. This behavior is consistent with the results of dark magnetoresistivity measurements at different temperatures. Our experiments demonstrate that photoconductivity is a very sensitive probe of the temperature variations of the transport properties, even those that are hardly detectable using standard transport measurements.