Z. D. Kvon

Quantum ratchet effects induced by terahertz radiation in GaN-based two-dimensional structures

Photogalvanic effects are observed and investigated in wurtzite (0001)-oriented GaN/AlGaN low-dimensional structures excited by terahertz radiation. The structures are shown to represent linear quantum ratchets. Experimental and theoretical analysis exhibits that the observed photocurrents are related to the lack of an inversion center in the GaN-based heterojunctions.

Two-dimensional electron-hole system in a HgTe-based quantum well

A two-dimensional electron-hole system consisting of light high-mobility electrons with a density of Ns = (4–7) × 1010 cm−2 and a mobility of μn = (4–6) × 105 cm2/V s and heavier low-mobility holes with a density of Ps = (0.7–1.6) × 1011 cm−2 and a mobility of μp = (3–7) × 104 cm2/V s has been discovered in a quantum well based on mercury telluride with the (013) surface orientation. The system exhibits a number of specific magnetotransport properties in both the classical magnetotransport (positive magnetoresistance and alternating Hall effect) and the quantum Hall effect regime. These properties are associated with the coexistence of two-dimensional electrons and holes.

Fast detector of the ellipticity of infrared and terahertz radiation based on HgTe quantum well structures

We report a fast, room temperature detection scheme for the polarization ellipticity of laser radiation, with a bandwidth that stretches from the infrared to the terahertz range. The device consists of two elements, one in front of the other, that detect the polarization ellipticity and the azimuthal angle of the ellipse. The elements, respectively, utilize the circular photogalvanic effect in a narrow gap semiconductor and the linear photogalvanic effect in a bulk piezoelectric semiconductor. For the former we characterized both a HgTe quantum well and bulk Te, and for the latter, bulk GaAs. In contrast with optical methods we propose is an easy to handle all-electric approach, which is demonstrated by applying a large number of different lasers from low power, continuous wave systems to high power, pulsed sources.

Conductivity of a two-dimensional electron gas in a Si/SiGe heterostructure near the metal-insulator transition: Role of the short- and long-range scattering potential

We report the observation of a metal-insulator transition (MIT) in a two-dimensional electron gas (2DEG) in a Si/SiGe heterostructure at zero magnetic field. On going through the MIT we observe the corresponding evolution of the magnetic field induced transition between the insulating phase and the quantum Hall (QH) liquid state in the QH regime. Similar to the previous reports for a GaAs sample, we find that the critical magnetic field needed to produce the transition becomes zero at the critical electron density corresponding to the zero field MIT. The temperature dependence of the conductivity in a metalliclike state at zero field is compared with the theory of the interaction corrections at intermediate and ballistic regimes

Cyclotron-resonance-assisted photcurrents in surface states of a three-dimensional topological insulator based on a strained high-mobility HgTe film

{k}_{B}T\ensuremath{\tau}/\ensuremath{\Elzxh}g~1.

Resonant circular photogalvanic effect in GaN/AlGaN heterojunctions

The theory yields a good fit for the linear part of the curve. However, the slope of that part of

Nonlocal transport near charge neutrality point in a two-dimensional electron-hole system.

{\ensuremath{\sigma}}_{\mathrm{xx}}(T)

Scattering processes in a two-dimensional semimetal

is about two times smaller than that reported in other 2D systems with similar values of

Giant photocurrents in a Dirac fermion system at cyclotron resonance

{r}_{s}.

Cyclotron resonance of Dirac ferions in HgTe quantum wells

At the same time, the recent theory of magnetoresistance due to electron-electron interaction in the case of arbitrary