Te Layers Research Articles

Cathodoluminescence and structural properties of ZnTe nanocrystals synthesized from Te/ZnO thin films

Highly mismatched alloys are of substantial interest for composition-dependent bandgap tunability for solar cell applications. Using low-energy ion implantation and subsequent thermal treatment, we have synthesized ZnTe nanocrystals from Te/ZnO bilayer thin films. However, only thermal treatment without ion implantation does not show any ZnTe nanocrystal characteristics that demonstrate the role of defects via ion implantation in nucleation growth. High-resolution transmission electron microscopy measurements confirmed the nanocrystalline growth of ZnTe and ZnTeO3 inside the mixed layer of ZnO and Te. From X-ray diffraction, it has been observed that a critical fluence of ions is required to produce a certain quantity of defects to assist in stoichiometric ZnTe formation. The absorption spectroscopy illustrates dual bandgap in the mixed alloys. Cathodoluminescence spectroscopy confirms two visible emission bands at 2.1 eV and 2.35 eV corresponding to the ZnTe and ZnO defect band along with the near band UV emission of ZnO at 3.26 eV. Such composition-dependent bandgap and light emission tunability from a mixed alloy are suitable for semiconductor device technology and energy harvesting.

Tunable negative photoconductivity in encapsulated ambipolar tellurene for functional optoelectronic device applications

Two-dimensional tellurium (2D Te) is a promising material for functional optoelectronic applications due to its narrow band gap and high carrier mobility. However, its light−matter interactions typically induce positive photoconductivity (PPC), leading to low photoresponsivity in 2D Te-based photodetectors due to their high dark current and the indirect 2D Te band gap. Here, we report novel tunable negative photoconductivity (NPC) in an Al2O3-encapsulated ambipolar 2D Te device, with excellent photoresponsivity of up to 6.9 × 104 A W−1, outperforming most previously reported 2D single-element chalcogen-based photodetectors. The NPC is attributed to the lower carrier mobility due to phonon scattering induced by the enhanced photothermal effect in the encapsulated Te layer. The threshold voltage can be tuned in the encapsulated 2D Te transistor under high-energy laser irradiation, demonstrating a new strategy for controlled 2D Te doping. Well-controlled gate-tunable negative and positive persistent photocurrents are achieved in the encapsulated 2D Te transistor, thus emulating biological synapse activity. An encapsulated 2D Te device with a flexible substrate also exhibits stable NPC after 1000 bending cycles, highlighting its potential use in wearable optoelectronic devices. The construction of ambipolar 2D Te phototransistors may pave the way for the development of novel functional optoelectronic devices.

Photocatalytic Oxidation in Few‐Layer Tellurene for Loss‐Invariant Integrated Photonic Resonance Trimming

AbstractTwo‐dimensional (2D) materials with unique physicochemical properties promote photocatalytic activities. As the 2D material composites research studies the statistical average of complex catalytic behaviors, an integrated photonic platform allows for clean and single flake level photo‐catalytic investigations with precisely quantified photocatalytic activities. In this paper, fluence‐dependent photo‐oxidation in two‐dimensional Tellurene (2D Te) is tracked by the evanescently coupled micro‐resonator. Nearly 32% of oxidation is achieved in ≈10 nm 2D Te flake, compared to only 4.5% oxidation in a 30 nm sample, probed by the resonance shift in silicon micro‐ring resonators substrate. The wider bandgap in the few layers of 2D Te allows faster charge transfer to adsorbed oxygen for a more efficient photocatalytic redox reaction. The photo‐oxidation in hybrid 2D Te results in invariant lineshapes of optical transmission resonance for wavelength trimming (more than 3× resonance bandwidth). The low threshold power, near‐infrared, and in‐waveguide resonance trimming scheme is compatible with most integrated photonic setups for easy fixing of the nanofabrication‐induced random resonance deviation for integrated photonic circuit applications in wavelength‐division‐multiplexing systems and spin qubits quantum computing.

Characterization of Cu(In,Ga)(Te,S)2 thin films grown on stainless steel foil substrates

In this study, Cu(In,Ga)(Te,S)2 (CIGTS) thin films with [Ga]/([In] ± [Ga]) atomic ratios in the ranges of 0.22–0.28 and 0.50–0.67 were fabricated using a two-stage technique. During the first stage of the technique, in one set of samples, Cu, In and Ga layers were deposited by electrodeposition on a Mo coated stainless steel (SS) foil substrate forming a SS/Mo/Cu/In/Ga precursor structure. For another set of samples, a Te layer was also deposited by e-beam evaporation on the SS/Mo/Cu/In/Ga structure forming a SS/Mo/Cu/In/Ga/Te precursor structure. During the second stage, SS/Mo/Cu/In/Ga and SS/Mo/Cu/In/Ga/Te stacks were reacted using rapid thermal annealing (RTA) for 5 min at 600 °C with or without presence of S vapors to produce CIGTS series thin films. SS/Mo/Cu/In/Ga stack under S atmosphere yielded CuInGaS2 with a Ga-In gradient across the thickness by RTA process. SS/Mo/Cu/In/Ga/Te stack reacted without S in the reaction atmosphere yielded the CuInGaTe2 compound. When S was present, the same stack with top Te layer yielded only CuInGaS2 compound. When, however, already formed CuInGaTe2 compound layers were heated in S environment at 400 °C, some Te could be retained in the films in the form of elemental Te. Gallium and In grading in various reacted films were evaluated by x-ray diffraction, secondary-ion mass spectrometry and EDS. CIGTS films showed highly (112) preferred oriented chalcopyrite phase and with the increase of Ga content, shifts were observed in the XRD peak positions demonstrating Ga inclusion in the lattice. Gibbs free energy calculations were used to explain the preferred reaction of S with metallic constituents when both S and Te were present for reaction.

Ga intercalation in van der Waals layers for advancing p-type Bi2Te3-based thermoelectrics

Tetradymite-structured chalcogenides, such as Bi2Te3 and Sb2Te3, are quasi-two-dimensional (2D) layered compounds, which are significant thermoelectric materials applied near room temperature. The intercalation of guest species in van der Waals (vdW) gap implemented for tunning properties has attracted much attention in recent years. We attempt to insert Ga atoms in the vdW gap between the Te layers in p-type Bi0.3Sb1.7Te3 (BST) for further improving thermoelectrics. The vdW-related defects (including extrinsic interstitial and intrinsic defects) induced by Ga intercalation can not only modulate the carrier concentration but also enhance the texture, thereby yielding excellent electrical properties, which are reflected in the power factor PF ∼ 4.43 mW⋅m−1⋅K−2. Furthermore, the intercalation of Ga produces multi-scale lattice imperfections such as point defects, Te precipitations, and nanopores, realizing the low lattice thermal conductivity in BST-Ga samples. Ultimately, a peak zT ∼ 1.1 at 373 K is achieved in the BST-1% Ga sample and greatly improved by ∼ 22% compared to the pristine BST. The weak bonding of vdW interlayer interaction can boost the synergistic effect for advancing BST-based or other layered thermoelectrics.

Layered Semiconductor Cr0.32Ga0.68Te2.33 with Concurrent Broken Inversion Symmetry and Ferromagnetism: A Bulk Ferrovalley Material Candidate.

The valleytronic state found in group-VI transition-metal dichalcogenides such as MoS2 has attracted immense interest since its valley degree of freedom could be used as an information carrier. However, valleytronic applications require spontaneous valley polarization. Such an electronic state is predicted to be accessible in a new ferroic family of materials, i.e., ferrovalley materials, which features the coexistence of spontaneous spin and valley polarization. Although many atomic monolayer materials with hexagonal lattices have been predicted to be ferrovalley materials, no bulk ferrovalley material candidates have been reported or proposed. Here, we show that a new non-centrosymmetric van der Waals (vdW) semiconductor Cr0.32Ga0.68Te2.33, with intrinsic ferromagnetism, is a possible candidate for bulk ferrovalley material. This material exhibits several remarkable characteristics: (i) it forms a natural heterostructure between vdW gaps, a quasi-two-dimensional (2D) semiconducting Te layer with a honeycomb lattice stacked on the 2D ferromagnetic slab comprised of the (Cr, Ga)-Te layers, and (ii) the 2D Te honeycomb lattice yields a valley-like electronic structure near the Fermi level, which, in combination with inversion symmetry breaking, ferromagnetism, and strong spin-orbit coupling contributed by heavy Te element, creates a possible bulk spin-valley locked electronic state with valley polarization as suggested by our DFT calculations. Further, this material can also be easily exfoliated to 2D atomically thin layers. Therefore, this material offers a unique platform to explore the physics of valleytronic states with spontaneous spin and valley polarization in both bulk and 2D atomic crystals.

Evolution of static charge density wave order, amplitude mode dynamics, and suppression of Kohn anomalies at the hysteretic transition in EuTe4

Charge density wave (CDW) induces periodic spatial modulation of the charge density that is commensurate or incommensurate with the host lattice periodicity, and leads to partial or complete electronic band-gap opening at the Fermi level (${E}_{\mathrm{F}}$). The recent finding of unconventional hysteresis within the CDW phase of ${\mathrm{EuTe}}_{4}$, not observable in other rare-earth tellurides $R{\mathrm{Te}}_{n}$ ($n=2$, 3), has highlighted the role of the relative phase of CDW distortion in weakly coupled Te layers. However, detailed structural and dynamical characterization of CDW distortion on the hysteretic transition is lacking. Here we report on the static CDW order, dynamics of the amplitude mode, and their evolution on the hysteretic transition using meV resolution elastic and inelastic x-ray scattering. We discover previously unidentified multiple commensurate and incommensurate CDW wave vectors ${\mathbf{q}}_{\mathrm{CDW}}$ along all three crystallographic axes. Importantly, we find that the previously reported $b$-axis CDW peak is coupled with the interlayer CDW phase and consequently co-occurs with the doubling of the unit cell along the $c$ axis. We confirm the presence of the competing $a$-axis CDW order but found it to be four orders of magnitude weaker than the $b$-axis CDW. Furthermore, we observe multiple Kohn anomalies at ${\mathbf{q}}_{\mathrm{CDW}}$ driven by Fermi surface nesting and hidden nesting, confirming earlier reports based on electronic and lattice susceptibility simulations. The amplitude mode and Kohn anomalies are found to suppress on unconventional hysteretic transition, suggesting the presence of nondegenerate metastable states, which we identify from the x-ray scattering measurements and simulations.

A study of interfacial electrical contact resistances of thermoelectric generators for hypersonic vehicles by experimental measurements and two-scale numerical simulations

An enormous amount of aerodynamic heat is produced on the surface of hypersonic vehicles, and the thermoelectric generator (TEG) technique holds the potential to convert aerodynamic heat into electric energy. In a TEG, the micrometer-scale roughness on TE legs and electrodes surfaces leads to the constriction of interfacial electric current and brings about electrical contact resistance (ECR). The heat transfer and conversion processes of a TEG are greatly influenced by such type of ECR. In this work, a TEG includes two ceramic substrates and a middle TE layer is established, and the TE layer consists of insulation material, N- and P-type TE legs and electrodes to connect the TE legs. The ECR and its effects on the TEG performance are studied by two-scale numerical simulations and experimental measurements. First, the practical topography of rough surfaces for TE legs and electrodes is measured, and the micrometer-scale ECR prediction numerical models are established based on the reconstructed topography. An ECR measurement platform is developed and the platform consists of a pressure device, power supply and data acquisition system which are used to provide loading pressures, voltage, and acquisition of electric current and voltage signals, respectively. The ECRs under different temperatures, loading pressures and gap mediums are then predicted and the numerical models are validated by a series of measurements. Second, the TE conversion process of TEG is simulated by a millimeter-scale model including insulation materials, TE legs, electrodes, and equivalent interfacial layers of ECR. The influence of ECR on the TE performance of TEG for the hypersonic vehicle is thus clarified.

Mn substitution in the topological metal Zr2Te2P

Results are reported for Mn intercalated Zr2Te2P, where x-ray diffraction , energy dispersive spectroscopy, and transmission electron microscopy measurements reveal that the van der Waals bonded Te–Te layers are partially filled by Zr and Mn ions. This leads to the chemical formulas Zr0.07Zr2Te2P and Mn0.06Zr0.03Zr2Te2P for the parent and substituted compounds, respectively. The impact of the Mn ions is seen in the anisotropic magnetic susceptibility, where Curie–Weiss fits to the data indicate that the Mn ions are in the divalent state. Heat capacity and electrical transport measurements reveal metallic behavior, but the electronic coefficient of the heat capacity (γ Mn ≈ 36.6 mJ (mol·K2)−1) is enhanced by comparison to that of the parent compound. Magnetic ordering is seen at K, where heat capacity measurements additionally show that the phase transition is broad, likely due to the disordered Mn distribution. This transition also strongly reduces the electronic scattering seen in the normalized electrical resistance. These results show that Mn substitution simultaneously introduces magnetic interactions and tunes the electronic state, which improves prospects for inducing novel behavior in Zr2Te2P and the broader family of ternary tetradymites.

Effects of absorber near-interface compensation on Cd(Se,Te) solar cell performance

Arsenic (As) has been shown to be an effective p-type dopant for CdTe, although high performance in As-doped devices remains difficult to achieve. Arsenic is prone to self-compensation in CdTe, as evidenced by the accumulation of dopant atoms in CdTe/Cd(Se,Te) near the interface with MgxZn1-xO (MZO). In this study, we use SCAPS 1D modeling software to investigate the effect of near-interface compensation, helping elucidate loss pathways in present-day As-doped devices and informing future growth directions. We consider three possible results of As accumulation: shallow donors, deep recombination centers, and a thin layer of excess acceptor accumulation. The reduction in near-interface carrier concentration caused by shallow donors is shown to improve open-circuit voltages (Voc), whereas deep levels are detrimental to all performance parameters. The thin charge layer affects capacitance-voltage (CV) measurements by reducing the depletion width while maintaining the same carrier concentration, replicating CV behavior that has been observed in actual devices. These results illustrate the importance of monitoring dopant accumulation within 100 nm of the interface, and suggest that reducing or eliminating the As concentration in this region would be beneficial. An undoped Cd(Se,Te) layer at the interface is suggested as a possible device structure to boost performance.

Selectively Modulated Photoresponse in Type‐I Heterojunction for Ultrasensitive Self‐Powered Photodetectors

AbstractPhotodetectors based on two‐dimensional (2D) van der Waals heterostructures (vdWHs) have demonstrated great potential in modern nanotechnologies across a wide range of applications. However, due to the severe interface recombination of the photogenerated electron–hole pairs and various absorption edges of constituent layers, they would suffer from low carrier collection efficiency, and the spectral response range of each constituent layer is indistinguishable. Herein, tellurium (Te) nanoflakes with broadband photoresponse are synthesized to construct type‐I InSe/Te vdWHs photodetector, which exhibits an ultralow reverse dark current of 3 × 10−14 A and an ultrahigh current rectification ratio of 108. Moreover, considerable photovoltaic effect of the heterostructure device is observed under illumination, attaining a light on/off ratio of up to 105, a high specific detectivity of 1.77 × 1011 Jones, and a fast response time of 320 µs. Based on type‐I band alignment, the Te layer can collect the photogenerated holes from the InSe layer to suppress the recombination of photogenerated carriers. More importantly, the spectral response of the InSe/Te heterostructure photodetector can be selectively modulated by the InSe layer. This work demonstrates that band alignment engineering of 2D vdWHs holds great potential for developing high‐performance self‐powered photodetectors.

New insights in GeTe growth mechanisms

The compound GeTe, despite its simple stoichiometry, is rather unconventional and has been investigated both from a fundamental and technological perspective: it is of high interest for several technologies such as data-storage (phase change memories) and thermoelectricity. The understanding of GeTe growth is thus a key issue for technological applications and fundamental understanding. In this work, GeTe crystallization kinetics is compared to Ge/Te reactive diffusion kinetics using in situ X-ray diffraction measurements, as well as in situ transmission electron microscopy. GeTe crystallization from an amorphous solid solution exhibiting the stoichiometry of the compound GeTe is found to occur at the same temperature as for the reactive diffusion of an amorphous Ge layer on top of a polycrystalline Te layer. Furthermore, GeTe growth is of tridimensional type in the two cases, and can be modeled by the Johnson-Mehl-Avrami-Kolmogorov model. Using this model, the activation energies of nucleation and growth were determined for both crystallization and reactive diffusion. The results suggest that GeTe exhibits nucleation/reaction kinetics unusually low compared to atomic transport kinetics, contrasting with other germanides.

Fe 5 Ge 2 Te 2 : Iron‐rich Layered Chalcogenide for Highly Efficient Hydrogen Evolution

Recent research on van der Waals (vdW) metal chalcogenides electrocatalysts for the hydrogen evolution reaction (HER) has been devoted to finding new catalysts with active basal planes. Here, we report on experimental and theoretical investigations of the HER activity of a recently discovered iron-rich vdW spintronic material, Fe5Ge2Te2 (FG2T) in alkaline media (1 M KOH). We show that a densified electrode of FG2T requires an overpotential of only −90.5 mV to drive a current density of 10 mA/cm2. Free energy calculations of hydrogen adsorption using density functional theory (DFT) proved that the numerous sites present on the hexagonal Te layer are more active than those found in the recently proposed Fe3GeTe2 (FGT) catalyst, supporting higher activity for the new Fe-richer catalyst. Like in FGT, XPS analysis has found that a thin oxide layer covers the active FG2T layers, suggesting the real active surface to be a hybrid FG2T/oxide layer. These results strengthen the idea of continued screening of iron-based vdW materials to replace the non-abundant platinum group electrocatalysts toward HER and other electrocatalytic processes.

Te3O5F2: a new metastable tellurium IV oxyfluoride with an acentric complex structure

The crystal structure of a new metastable tellurium (IV) oxyfluoride Te3O5F2 [non-centrosymmetric P21 space group] is unusually complex with 15 different Te polyhedra. It is built of giant cylindrical columns of oxide units connected via weak Te-F bonds. A strict O/F order is evidenced and a structural comparison with Sb3O2F5 shows that these two phases derive, by a different mechanism, from the anion-excess fluorite superstructure type. Surprisingly, in these two structures is observed a full gradation of various polyhedra of tellurium (IV) or antimony (III) with the oxygen atom ensuring a strong framework at the centre of these structures (cylinders for Te phase and layers for Sb one), and more and more F anions moved away at the periphery of these strong units, connecting these units via weak Te-F or Sb-F bonds. This well illustrates the different roles played by oxygen and fluorine atoms in the oxyfluorides of cations presenting an electronic lone pair E (5s2 in the case of Te4+ cation), in relation with the non-linear properties of these phases.

Anisotropic superconducting properties of FeSe0.5Te0.5 single crystals

We investigated the anisotropic electrical transport and magnetic properties of FeSe0.5Te0.5 single crystals grown by the self-flux method. The in-plane resistivity shows a metallic-like temperature dependence, while the out-of-plane resistivity shows a broad hump with a maximum at around 64 K. The magnetization loops for H//c-axis and H//ab-plane are also different, for example, there is a typical second peak for H//c-axis. The in-plane critical current density is larger than the out-of-plane one. The coherence length and penetration depth were estimated by the Ginzburg–Landau theory. The anisotropic parameter γ depends on the applied magnetic field and the temperature. The coupling of superconducting FeSe(Te) layers and the flux pinning mechanism relevant to anisotropy are also discussed.

Growth of high-quality semiconducting tellurium films for high-performance p-channel field-effect transistors with wafer-scale uniformity

Achieving high-performance p-type semiconductors has been considered one of the most challenging tasks for three-dimensional vertically integrated nanoelectronics. Although many candidates have been presented to date, the facile and scalable realization of high-mobility p-channel field-effect transistors (FETs) is still elusive. Here, we report a high-performance p-channel tellurium (Te) FET fabricated through physical vapor deposition at room temperature. A growth route involving Te deposition by sputtering, oxidation and subsequent reduction to an elemental Te film through alumina encapsulation allows the resulting p-channel FET to exhibit a high field-effect mobility of 30.9 cm2 V−1 s−1 and an ION/OFF ratio of 5.8 × 105 with 4-inch wafer-scale integrity on a SiO2/Si substrate. Complementary metal-oxide semiconductor (CMOS) inverters using In-Ga-Zn-O and 4-nm-thick Te channels show a remarkably high gain of ~75.2 and great noise margins at small supply voltage of 3 V. We believe that this low-cost and high-performance Te layer can pave the way for future CMOS technology enabling monolithic three-dimensional integration.

Conductometric NO2 gas sensor based on nanolayered amorphous tellurium for room temperature operation

A fast operating NO2 sensor based on amorphous Te layer of a nanometric thickness, enclosed between Pt electrodes has been developed and investigated. The gas sensor operates at room temperature and by sensitivity ~ 60% / ppm it exhibits a response time around 5 s. The long – term stability of the sensor tested by operating it 12 weeks showed no appreciable changes in the characteristics. To elucidate the mechanism of so fast gas detection, the sensor structure and active material have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM), being followed with its characterization via studying the current - voltage characteristics, dynamic response, long – term stability, effects of temperature, humidity and other gases. It is shown that combination of used materials as well as the developed sensor design allow the simultaneous involvement of contact, and surface phenomena in sensor mechanism of operation, making possible the gas induced modulation of charge carriers simultaneously on Te film surface, accumulation regions at contacts, which include the portions of the degenerate (metallic) p-Te, as well as in contact gaps (transition regions), originated from microscopically roughness, formed since during electrode deposition. The last referred process leads to increasing the portion of the semiconducting Te nanolayer turned into metal of p-type Te, which at closed – circuit conditions results in a sharp increasing of the current flow through the device. Such explanation of obtained results reflects the fundamentals of metal – semiconductor junctions, the properties of used materials and meets the modern models proposed for interpretation of adsorption processes in similar devices.

Development of arsenic doped Cd(Se,Te) absorbers by MOCVD for thin film solar cells

Recent developments in CdTe solar cell technology have included the incorporation of ternary alloy Cd(Se,Te) in the devices. CdTe absorber band gap grading due to Se alloying contributes to current density enhancement and can result in device performance improvement. Here we report Cd(Se,Te) polycrystalline thin films grown by a chamberless inline atmospheric pressure metal organic chemical vapour deposition technique, with subsequent incorporation in CdTe solar cells. The compositional dependence of the crystal structure and optical properties of Cd(Se,Te) are examined. Selenium graded Cd(Se,Te)/CdTe absorber structure in devices are demonstrated using either a single CdSe layer or CdSe/Cd(Se,Te) bilayer (with or without As doping in the Cd(Se,Te) layer). Cross-sectional TEM/EDS, photoluminescence spectra and secondary ion mass spectroscopy analysis confirmed the formation of a graded Se profile toward the back contact with a diffusion length of ~1.5 μm and revealed back-diffusion of Group V (As) dopants from the CdTe layer into Cd(Se,Te) grains. Due to the strong Se/Te interdiffusion, CdSe in the Se bilayer configuration was unable to form an n-type emitter layer in processed devices. In situ As doping of the Cd(Se,Te) layer benefited the device junction quality with current density reaching 28.3 mA/cm 2 . The results provide useful insights for the optimisation of Cd(Se,Te)/CdTe solar cells. Compositional control of optical band gap in Cd(Se,Te) thin films (0 ≤ x ≤ 1) (left) and the Se profile in finished Cd(Se,Te) devices (right) fabricated by MOCVD. • Cd(Se,Te) thin films (0 ≤ x ≤ 1) deposited with linear compositional control using a chamber-less MOCVD process. • CdSe-only and CdSe/CdSe 0.2 Te 0.8 bilayers utilised for Cd(Se,Te) grading in devices. • In-situ and ex-situ group V (arsenic) doping of the graded Cd(Se,Te) obtained. • Device performance improved for thinner CdSe layers and in-situ doped bilayers. • Good control of Se profile achieved via CdSe and CdSe/CdSe 0.2 Te 0.8 properties.

Influence of Te layer on CdTe thin films and their performance on CdS/CdTe solar cells

CdTe semiconductor is an absorbent material used in “tandem” photovoltaic solar cells. This material is commonly deposited by thermal evaporation presenting electrical resistivity values about of 105 W·cm to 109 W·cm. CdTe is applied in thin solar cells as p-type layer which is in contact with metal back electrode in solar cells. In the CdTe/metal junction a Schottky barrier exits; and small number of charge carriers have enough energy to get over the barrier and cross to the metal back contact. To solve part of this problem, nanostructured Te thin films were used as intermediate layers between CdTe and metal contact. Te layers whit different physical properties were deposited on CdS/CdTe structure by thermal evaporation employing different growth parameters. The electrical parameters of CdTe solar cells were influenced by p+ Te regions. p+ Te regions used as intermediate layer with large deposition time increases the FF and VOC values from 30% to 60% and 560 mV to 730 mV respectively. Also, the electrical resistivity is reduced from 106 W·cm to 103 W·cm. In this sense, Te region implemented as nanostructure allows to reduce the series resistance from 99 W to 20 W and increases the shunt resistance from 1445 W to 4424 W; Te region as thin films demonstrated not be adequate.

THz polarization-dependent response of antenna-coupled HgCdTe photoconductors under an external constant electric field

The photoresponse of antenna-coupled Hg1-x Cd x Te (x ≈ 0.201) narrow-gap epitaxially grown photoconductors with normal band ordering having large spin–orbit coupling and being irradiated by the normal to the photoconductor surface terahertz (THz) radiation (linearly or circularly polarized), is investigated at T = 80 and 300 K. The oscillations of polarized photoresponse in biased and unbised structures were revealed. In experiments, Hg1-x Cd x Te layers (point group ) grown on (013) GaAs substrates were used. In biased structures, to the ordinary charge current and Rashba spin splitting current in zero electric field, an additional polarized current, which grows with the external electric field strength, arises. Presumably, the oscillating photoresponses under polarized THz radiation in these unbiased and biased structures are connected with the circular and linear photogalvanic effects without and with an external electric field. The observed features of the polarized dependent photoresponse can be important for spintronics applications at elevated temperatures.