Terahertz magneto-spectroscopy of a point contact based on CdTe/CdMgTe quantum well

Abstract

To understand a terahertz (THz) response of a point contact device, a number of samples based on CdTe/CdMgTe quantum wells grown by a molecular beam epitaxy were investigated at low temperatures and high magnetic fields. The experiments involved magnetotransport, photocurrent, and transmission measurements carried out with monochromatic THz sources or a Fourier spectrometer. Samples of different geometry with and without gate metallization were used. We observed excitations of a two-dimensional electron plasma in the form of optically induced Shubnikov-de Haas oscillations, cyclotron resonance transitions, and magneto-plasmon resonances. A polaron effect was observed at magnetic fields higher than 10 T. A point contact device processed with an electron beam lithography was investigated as a detector of THz radiation. It was shown that the main mechanism responsible for a THz performance of the point contact was excitation of magneto-plasmons with a wavevector defined by geometrical constrictions of the device mesa.

Polarization of Magnetoplasmons in Grating Metamaterials Based on CdTe/CdMgTe Quantum Wells

“…Second, we showed that we were able to generate and transmit circularly polarized radiation to the sample cooled to a low temperature, which is confirmed by the red curve in Figure 6. Third, based on earlier studies on magnetoplasmons in CdTe-based QWs [25][26][27], we state that the resonances observed in Figure 6 on the etched sample were due to the excitation of a magnetoplasmon, which appeared not to be circularly polarized.…”

Grating Metamaterials Based on CdTe/CdMgTe Quantum Wells as Terahertz Detectors for High Magnetic Field Applications

“…On the other hand, interaction of THz radiation with CdTe-related materials, bulk or two-dimensional, did not attract a large interest in the past but this situation has been changing because observation of quantum effects in a 2DEG in CdTe-based QWs became possible due to technological developments of the growth of the quantum structures [21]. A sufficiently high mobility of electrons allowed for observation of the CR and magnetoplasmon (MP) excitaitions in such high quality samples [23,24]. These excitations can be observed at THz frequencies at quantizing magnetic fields.…”

“…In our recent studies [23,24] we concentrated on plasmonic excitations in CdTe/CdMgTe structures with one modulation doped QW. A metallic grating prepared on the surface of samples allowed to excite MPs with monochromatic THz radiation.…”

“…Basic information about MP excitations in different types of CdTe, GaAs and GaN-based heterostructures and QWs can be found in our previous papers [12,23,24,[27][28][29][30] (for a general review concerning the physics of plasmons in a 2DEG, we recommend Kushvaha [31]). Generally, MPs can be excited with radiation of the frequency ω exc at magnetic field B (perpendicular to a 2DEG) which satisfies the relation:…”

Photoluminescence of CdTe/CdMgTe Double Quantum Wells with a Two-Dimensional Electron Gas

“…Magnetoplasmons in CdTe were previously studied in less complicated structuressingle CdTe/CdMgTe quantum well doped with iodine donors in a quantum point contact or grid-gate geometry [3][4][5]. A photoluminescence characterization of samples is one of necessary steps towards measurements in which a coupling of two types of excitations -a visible one and a THz one -are active.…”