Terahertz response of CdTe/Cd1-xMgxTe modulation-doped multiple quantum wells

Terahertz (THz) transmission, photoresistance, and electrical conductivity experiments were carried out at 4.2 K on a sample with modulation-doped CdTe/Cd₁₋ₓMgₓTe multiple quantum wells. The measurements were carried out as a function of a magnetic field 𝐵 up to 9 T and a radiation frequency between 0.1 and 0.66 THz. A broad minimum in the transmission curve was observed at magnetic fields corresponding to the cyclotron resonance at given THz frequency which was followed at larger fields by an oscillatory signal, periodic in 𝐵ˉ¹. Shubnikov-de Haas oscillations were observed in magnetoconductivity and in photoresistance. Each of these experimental signals revealed the same electron concentration equal to (1.01 ± 0.03) ∙10¹² cmˉ². THz spectroscopy results are compared with data obtained on a single quantum well and are discussed from the point of view of using such multiple quantum wells as THz optical elements.

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1. Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023).

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2. This research was partially supported by the Polish National Science Centre grant UMO-2019/33/B/ST7/02858 and by the Foundation for Polish Science through the IRA Programme co-financed by EU within SG OP (Grant No. MAB/2017/1).