Hall Measurement Technique Research Articles

Lateral Electronic Junction of a Single Ultrathin Silicon Induced by Interfacial Dipole of Self-Assembled Monolayer.

Interface engineering is pivotal for enhancing the performance and stability of devices with layered structures, including solar cells, electronic devices, and electrochemical systems. Incorporating the interfacial dipole between the bulk layers effectively modulates the energy level difference at the interface and does not significantly influence adjacent layers overall. However, interfaces can drastically affect adjoining layers in ultrathin devices, which are essential for next-generation electronics with high integrity, excellent performance, and low power consumption. In particular, the interfacial effect is pronounced in ultrathin semiconductors, which have a weak electric field screening effect. Herein, the substantial interfacial impact on the ultrathin silicon is shown, the p- to n-type inversion of the semiconductor solely through the deposition of a self-assembled monolayer (SAM) without external bias. The effects of SAMs with different interfacial dipoles are investigated by using Hall measurement and surface analytic techniques, such as UPS, XPS, and KPFM. Furthermore, the lateral electronic junction of the ultrathin silicon is engineered by the regioselective deposition of SAMs with opposite dipoles, and the device exhibits rectification behavior. When the interfacial dipole of SAM is manipulated, the rectification ratio changes sensitively, and thus the fabricated diode shows potential to be developed as a sensing platform.

Study of Near Band Edge Emission Spectra and Conductivity Transformation in Fe‐Doped Cadmium Telluride Nanoparticles for the Device Applications

AbstractThe research work discussed here explains the near band edge emission and conductivity transformation of the Fe‐doped CdTe nanoparticles synthesized by hydrothermal method by using an autoclave. The size of the undoped CdTe nanoparticles is found to be 5.48, 8.45, 9.40, and 14.79 nm, respectively for the nanoparticles collected at 15, 30, 45, and 60 minutes of duration of the synthesis. Whereas for the Fe‐doped CdTe nanoparticles, the size is found to be 12.81, 16.9, and 18.5 nm, respectively for the 10%, 20%, and 30% Fe concentrations as doping elements in CdTe nanoparticles. The XPS spectra clearly show the successful doping of Fe in the CdTe QDs and also the orbital state of Fe in CdTe. The EDAX spectra is taken to trace the elements present in the synthesized nanoparticles. From the UV–vis absorption spectrum, the band gap is found to decrease when doped with Fe in different concentrations. Also, an appreciable blue shift is found in the as synthesized undoped and Fe‐doped CdTe NPs. A near band edge emission property is observed for the Fe‐doped CdTe NPs when doped with different Fe concentrations. The van der Pauw Hall measurement technique is employed to study the electrical properties such as conductivity, carrier concentration, mobility, and Hall coefficient of the undoped and Fe‐doped CdTe nanoparticles. The consistent p‐type conductivity is observed for the undoped CdTe nanoparticles till the time duration of 45 minutes of synthesis. When doped with Fe in 30% concentration, the type of conductivity is found to transform from p‐type to n‐type. The luminescence property between 450 and 500 nm makes these materials suitable for device applications like light‐emitting diodes. Also, the study of Hall measurement here explains the application of these materials as photovoltaic cells.

Anomalous hall and skyrmion topological hall resistivity in magnetic heterostructures for the neuromorphic computing applications

Topologically protected spin textures, such as magnetic skyrmions, have shown the potential for high-density data storage and energy-efficient computing applications owing to their particle-like behavior, small size, and low driving current requirements. Evaluating the writing and reading of the skyrmion’s magnetic and electrical characteristics is crucial to implementing these devices. In this paper, we present the magnetic heterostructure Hall bar device and study the anomalous Hall and topological Hall signals in these devices. Using different measurement techniques, we investigate the magnetic and electrical characteristics of the magnetic structure. We measure the skyrmion topological resistivity and the magnetic field at different temperatures. MFM imaging and micromagnetic simulations further explain the anomalous Hall and topological Hall resistivity characteristics at various magnetic fields and temperatures. The study is extended to propose a skyrmion-based synaptic device showing spin-orbit torque-controlled plasticity. The resistance states are read using the anomalous Hall measurement technique. The device integration in a neuromorphic circuit is simulated in a 3-layer feedforward artificial neural network ANN. Based on the proposed synapses, the neural network is trained and tested on the MNIST data set, where a recognition accuracy performance of about 90% is achieved. Considering the nanosecond reading/writing time scale and a good system level performance, these devices exhibit a substantial prospect for energy-efficient neuromorphic computing.

Investigation of persistent photoconductance and related electron mobility in thin IGZO layers with the PDL Hall technique

Indium gallium zinc oxide (IGZO) is a popular material to fabricate thin-film transistors (TFT). The light induced long-term conductance change in the thin IGZO layers (known as persistent photoconductance, PPC) is a significant phenomenon that should be deeply understood and controlled. We used the Parallel dipole line (PDL) AC Hall measurement technique to study the light induced change of the conductance and mobility of charge carriers in IGZO layers and its relaxation in dark. In the PDL systems rotating permanent magnets are applied to realize the AC Hall measurement at large magnetic field with harmonic modulation in a very compact design. Several samples with varying layer thickness, composition, and passivation conditions were prepared to investigate the PPC phenomenon. The magnitude and relaxation of PPC show a very strong dependence on IGZO preparation conditions. In some samples over tenfold conductance increase was observed at room temperature. Relaxations times varied from a few hours up to a few days. An interesting observation was that the mobility (in the range of 1 cm2/Vs-8.9 cm2/Vs) also increases with the conductance as the result of illumination.

Comparison of Sputtered and Evaporated Vanadium Pentoxide Thin Films for Resistive Microbolometer Application

V2O5 thin films have made impressive progress in the development of resistive microbolometers. The challenging parameters for microbolometers are the active material selection and the deposition methods. It might be a more promising way to achieve a good performance of the devices. The present work deals with the V2O5 thin films fabricated on soda lime glass substrates by using e-beam evaporation and magnetron sputtering techniques at a substrate temperature of 200 °C. Afterward, samples were annealed at 300 and 400 °C for 1 h to obtain uniform and stoichiometric thin films. X-ray Diffraction (XRD) showed that the thin films deposited by magnetron sputtering were amorphous in nature, even after annealing at elevated temperatures; however, the thin films fabricated by the electron beam evaporation technique show crystalline nature, which was improved by annealing. XRD also revealed various mixed phases of VOx in electron beam-deposited films. Optical properties were determined using UV-Visible spectroscopy, which showed a decrease in transmittance from 81% down to 57% by increasing the annealing temperature. Similarly, the band gap calculated for electron beam evaporated and magnetron sputtered V2O5 thin films was observed in the range of 1.41 to 2.25 eV. Rutherford backscattering (RBS) was performed to determine the thickness and composition of the films. Slight variations have been observed in intended and deposited thicknesses of films fabricated by e-beam and sputtering techniques. Structural properties revealed by Field Emission Scanning Electron Microscope (FESEM) were found to be the uniform, compact and dense surface of the as-deposited and 300 °C annealed samples. However, annealing at 400 °C changed the surface morphology into nanorods in e-beam and plate-like structures in the sputtered film. EDS proved the elemental concentration of vanadium and oxygen in these V2O5 thin films. Electrical properties were investigated using the Hall measurement technique which showed better conductivity of sputtered films than e-beam deposited films. It can be concluded that the cost-effective and reliable microbolometers infrared (IR) sensors can be fabricated using annealed sputtered films.

Signatures of ferromagnetism in p-type cadmium telluride quantum dots

Signatures of Ferromagnetism in p-type conducting Cadmium Telluride (CdTe) quantum dots (QDs), synthesized by Single Injection Hydrothermal (SIH) method are reported in this article. The Powder X-ray Diffraction (P-XRD) analysis depicts hexagonal structure for the CdTe QDs. X-ray Photoelectron Spectroscopic (XPS) technique is used to determine the 3d5/2, 3d3/2 orbital states of the Cd as well as Te and also to confirm the Cd-Te bond formation in CdTe QDs. The van der Pauw Hall measurement technique is used to identify the p-type conductivity in the CdTe QDs, which are attributed to the Cd vacancy defects formed during the synthesis of the CdTe QDs. Appearance of hysteresis in the Superconducting Quantum Interference Device (SQUID) measurements made at 300 K and 5 K, confirm the ferromagnetic behavior of the CdTe QDs. The signatures of ferromagnetism are attributed to Cd vacancy defects.

Fabrication of inverted ZnCuInS/ZnS based quantum-dot light-emitting diodes with the non-stoichiometric ZnO layers

The performance of the Cd-free quantum-dot light-emitting diode was investigated using un-doped and non-stoichiometric sputtered ZnO. Highly conductive metallic ZnO was sputtered with the presence of pure argon (Ar) gas, where the thickness was varied to enhance the structural, morphological, and electrical properties. The electrical properties of the fabricated ZnO were measured using the Hall measurement technique. Consequently, the device performance was validated by the mobility and carrier concentration of the sputtered ZnO film. In addition, from the X-ray diffraction analysis, it was confirmed that the ZnO film was grown on c(002)-axis orientation, parallel to the substrate surface. The morphological properties were also observed using a field-emission-scanning electron microscope to integrate with the crystalline growth conditions of XRD analysis. The external quantum efficiency of 1.02% and current efficiency of 1.86 cd A−1 were achieved with the mobility of 15.1 cm2 V−1 s−1 and carrier concentration of 2.94 × 1020 cm−3 of the ZnO film.

Enhanced thermoelectric performance of nanostructured manganese telluride via antimony doping

Abstract Manganese telluride is a good thermoelectric material for medium temperature applications. Pristine MnTe is a p-type semiconductor with an average hole concentration of 10 19 c m − 3 . Many dopants like Sodium, Copper and Sulphur were incorporated in the MnTe and their thermoelectric properties were studied. Antimony is an ideal dopant to alter the thermoelectric properties. Compounds belonging to the series M n 1 − x S b x T e with (x = 0, 0.005, 0.01, 0.015, 0.02) were prepared using a combination of High Energy Ball Milling (HEBM), melt quenching and hot press techniques. Structural, electrical and thermo-electric properties of these compounds were determined. Carrier concentration and mobility were measured by Hall measurement techniques. Charge carrier concentration increases with Sb doping while mobility and effective mass decreases. Seebeck coefficient and electrical conductivity were measured in the temperature range 100 K–730 K, and thermal conductivity was evaluated in the temperature range 100 K–300 K. The power factor and figure of merit (ZT) were also estimated. The highest power factor achieved is at 730 K and is 1768 μ W m − 1 K − 2 for M n 0.98 S b 0.02 T e . The highlight of the present study is the rise in electrical conductivity and reduction in the thermal conductivity with Sb doping.

Carrier-resolved photo-Hall effect.

The fundamental parameters of majority and minority charge carriers-including their type, density and mobility-govern the performance of semiconductor devices yet can be difficult to measure. Although the Hall measurement technique is currently the standard for extracting the properties of majority carriers, those of minority carriers have typically only been accessible through the application of separate techniques. Here we demonstrate an extension to the classic Hall measurement-a carrier-resolved photo-Hall technique-that enables us to simultaneously obtain the mobility and concentration of both majority and minority carriers, as well as the recombination lifetime, diffusion length and recombination coefficient. This is enabled by advances in a.c.-field Hall measurement using a rotating parallel dipole line system and an equation, ΔμH=d(σ2H)/dσ, which relates the hole-electron Hall mobility difference (ΔμH), the conductivity (σ) and the Hall coefficient (H). We apply this technique to various solar absorbers-including high-performance lead-iodide-based perovskites-and demonstrate simultaneous access to majority and minority carrier parameters and map the results against varying light intensities. This information, which is buried within the photo-Hall measurement1,2, had remained inaccessible since the original discovery of the Hall effect in 18793. The simultaneous measurement of majority and minority carriers should have broad applications, including in photovoltaics and other optoelectronic devices.

Self-doped SnO2:F synthesis by aerosol-spray deposition technique and their application in relative humidity sensor devices

Fluorine-doped tin-oxide (SnO2:F) thin films were prepared by aerosol-spray deposition technique on soda lime glass substrate by one-step deposition process. Tin (II) fluoride (SnF2) was used as source of tin (Sn) and doping element fluorine (F), to synthesis a self-doped transparent conducting electrode. The doping concentration of the thin films was controlled by varying deposition temperature and the molar concentration of the SnF2 solution. Electrical resistivity of the samples was measured by Van Der Pauw method and the mobility was calculated by Hall measurement technique. SnO2:F thin films grown under optimum condition showed 1.2 × 10−4 Ω-cm resistivity and 6.5 × 1020/cm3 carrier concentration. Surface-free energy of the deposited thin films was calculated from the measurement of contact angle for three different probe liquids using the Wendt theory. Sample grown at optimum condition showed the lowest surface-free energy of 63.55 mJ/m2 with dominating polar component. Reduced graphene oxide was used to produce a resistive humidity-sensing device to study the effectiveness of FTO thin film as back electrode. Maximum of 18.27% responsivity was observed for the relative humidity of 90% along with the sensitivity of 1.16 Ω/% RH.

Variation of Optical and Electrical Properties of Zr Doped TiO2 Thin Films with Different Annealing Temperatures

Zr doped (0.01M) TiO2 thin films were fabricated by unconventional sol-gel technique starting from powder precursors. Using microscopic glass slide, the films were deposited and annealing was done at different temperatures. In order to study the structural properties of these fabricated films x-ray diffraction has been adopted. Similarly, for the study of optical and electrical properties, UV-VIS spectrophotometer and Hall measurement techniques have been adopted for all the fabricated samples. It is found that the doped TiO2 thin film annealed at 350 °C showed a reduced band gap value in comparison to other films. This sample is also found to have highest optical and electrical conductivity which makes it suitable for light harvesting. Our result shows that Zr doped TiO2 thin film annealed at 350 °C plays an important role in tuning the properties for device applications.

Study of closed-tube Cd diffusion in InSb for mid-IR detector-based applications

Diffusion process of Cadmium (Cd) in indium antimonide (InSb), in a closed tube system, was studied using Hall measurement technique. Various experiments are carried out to achieve a suitable and sustainable procedure. Process details are reported and discussed in the context. Impurity concentration profiles are modeled using an optimized interstitial-substitutional approach. These Mathematical models are in good agreement with experimental data and can be employed in numerical simulations of InSb-based devices.

Probing into the optical and electrical properties of hybrid Zn1−xCoxSe thin films

Probing into the elemental composition, structural, morphological, optical and electrical transport properties of chemically deposited Zn1−xCoxSe (0 ≤ x ≤ 0.275) thin films with a special emphasis given to the Co2+-concentration is presented in this paper. Elemental and structural analysis confirmed the successful realization of Co(ZnSe) thin films. Addition of Co2+ into ZnSe host lattice caused morphological changes from globule like morphology to the formation of leaf like appearance composing the disc-decked micro-flakes elongated in size. The optical studies done in the range of wavelengths between 350 to 1200 nm showed a slight red shift in the optical spectrum with increased Co2+ concentration in the ZnSe matrix. Effect of increased impurity addition is also reflected in the band gap measurements that a decrease in the bandgap, typically from 2.71 to 1.96 eV, is observed for an increase in Co2+ concentration from x = 0–0.275. The other optical parameters namely, refractive index, extinction coefficient, power factor and dielectric constants were determined from these studies and other variations are adequately explained as a special reference to the Co-concentration. The composition dependence of the electrical transport characteristics were studied using the two-probe and Hall measurement techniques. The effect of Co-concentration on the transport characteristics has been studied and mechanism of an electrical conduction is discussed. A continuous increase in an electrical conductivity with n-type conduction has been observed for these samples.

Effect of Nb doping on the structural, morphological, optical and electrical properties of RF magnetron sputtered In2O3 nanostructured films

Undoped and niobium (Nb) doped indium oxide (In2O3) thin films are prepared by radio frequency magnetron sputtering technique. The effect of Nb on the structural, morphological, optical and electrical properties of In2O3films are analyzed using techniques such as X‐ray diffraction (XRD), micro‐Raman spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy, UV–visible spectroscopy, spectroscopic ellipsometry, photoluminescence spectroscopy and Hall effect measurements. XRD analysis reveals that the as‐deposited undoped and Nb doped films are polycrystalline in nature with cubic bixbyite structure. Raman analysis supports the presence of cubic bixbyite structure of In2O3in the films. XPS analysis shows a decrease of oxygen deficiency due to Nb and the existence of Nb as Nb4+ in the In2O3lattice. The band gap energy of the films increases with increase in Nb concentration. PL spectra reveal intense UV and visible emissions in all the films. Optical constants of the films are determined using spectroscopic ellipsometry. The thickness of films estimated using FESEM and ellipsometry are in good agreement. The carrier concentration, mobility and nature of carriers are measured using Hall measurement technique in Van der Pauw configuration at room temperature.

Fabrication and Characterization of SiGe on Insulator through Condensation and Wafer Bonding Techniques

SiGe on insulator (SGOI) is desired to obtain microelectronic devices with high performance and low leakage current. The manufacturing of silicon on insulator (SOI) has been already developed and the wafers are on the market with different expenses and qualities. Nevertheless the fabrication techniques of SGOI is more complex than SOI wafers. In this study two different techniques has been applied to fabricate SGOI wafers. The advantages and disadvantages of both techniques have been discussed in details and the wafers have been characterized in terms of defect density, roughness, uniformity and fabrication process parameters. The original wafers for condensation technique were SOI with 50 nm Si top and 400 nm buried oxide. The 100 nm Si0.74Ge0.26 was epitaxially grown on SOI wafers followed by 10 nm Si cap layer using chemical vapor deposition (CVD) technique. The Si cap/ Si0.74Ge0.26/ Si structure went through condensation where Si cap layer oxidize immediately and Si0.74Ge0.26/Si was sandwiched between two oxide layers. The consequence of Ge diffusion to the beneath Si layer result single layer Si0.53Ge0.47on insulator (SGOI). In the wafer bonding technique as second method, Si0.53Ge0.47 has grown epitaxially on a Si wafer. The direct bonding applied between donor and acceptor wafers. The bonded wafers are then annealed in order to strength the bonding. The etch-back process begins by thinning down the donor wafer to leave the Si0.53Ge0.47 on insulator. The quality and electrical transport of condensed and bonded SiGe layer were examined using high resolution reciprocal lattice mapping (HRRLM), scanning electron microscopy (SEM), Rutherford back scattering (RBS), atomic force microscopy (AFM), hall measurement technique in van der pauw structure and four probe measurement technique. The results show the condensation layer undergo defects which originate from condensation process compared to bonding layer which possess lower defect density. This study will help to continue optimizing of substrate engineering of group IV alloys for implementation on next silicon technology.

A study on 100 MeV O7+ irradiated SnO2/Ag/SnO2 multilayer as transparent electrode for flat panel display application

The multilayer thin films of SnO2/Ag/SnO2 were deposited using electron-beam and thermal evaporation for flat panel display application. The as-prepared SnO2/Ag/SnO2 specimen was irradiated with 100MeV O7+ ions by varying the fluences 1×1012 and 5×1012ions/cm2. The pristine and irradiated films were investigated using XRD, SEM, AFM and Raman to find out modification in the structure and surface morphology of the films. UV–Vis and Hall measurement techniques were used to investigate the optical and electrical properties respectively. It was observed that the roughness of the film after irradiation (for the fluence of 1×1012ions/cm2) ​ decreased to 0.68nm from 1.6nm and showed an increase in roughness to 1.35nm on increasing the fluence to 5×1012ions/cm2. This oxide/metal/oxide structure fulfills the basic requirements of a TCE, like high-transmittance >75% for pristine and >80% for the fluence of 1×1012ions/cm2 over a broad spectrum of visible light for practical applications. The multilayer structure shows change in the electrical resistivity from 1.6×10−3Ωcm to 6.3×10−3Ωcm after irradiation.

Role of magnesium in ZnS structure: Experimental and theoretical investigation

Wide band gap semiconductor materials are extending significant applications in electronics and optoelectronics industry. They are showing continued advancement in ultraviolet to infrared LEDs and laser diodes. Likewise the band gap tunability of ZnS with intentional impurities such as Mg and Mn are found useful for optoelectronic devices. Information from literature indicates slight blue shift in the band gap energy of ZnS by Mg doping but nevertheless, we report a reasonable red shift (3.48 eV/356 nm to 2.58 eV/480 nm) in ZnS band gap energy in Mg-ZnS structure. Theoretical model based on first principle theory using local density approximation revealed consistent results on Mg-ZnS structure. Similarly, structural, morphological, optical and electrical properties of the as grown Mg-ZnS were studied by XRD, SEM, FTIR, EDS, UV-Vis Spectrophotometer and Hall measurement techniques.

Plasma treated graphene oxide films: structural and electrical studies

The exfoliation of oxygenated functional groups from 60 W hydrogen plasma treated graphene oxide films was investigated using X-ray diffractometric (XRD), Raman spectroscopic and atomic force microscopic techniques. The interlayer spacing of the graphene oxide sheets was found from the XRD pattern to decrease from 0.88 to 0.35 nm after plasma treatment. The reduced intensity ratio of the D and G peaks of the Raman spectra indicates a decrease in the crystallite size of the sp 2 domains due to plasma treatment. Atomic force microscope showed the continuous morphology of the plasma treated film. The electrical properties of plasma treated samples spin-coated on silicon were studied using Van Der Pauw and non contacting microwave techniques. The sheet resistivity determined from Van der Pauw measurements was $$1.62\,{\text{M}}\Omega /{\text{sq}}$$ , yielding the value of $$3.1\,{\text{S}}\,{\text{m}}^{ - 1}$$ for the bulk conductivity. The charge mobility of $$3.8\,{\text{m}}^{2} \,{\text{V}}^{ - 1} \,{\text{s}}^{ - 1}$$ has been determined from Hall measurement technique.

Defect analysis in fast electron irradiated silicon by Hall and magnetoresistivity means

Two sets of p- and n-conductivity type silicon samples have been irradiated by 6.6MeV electrons with fluence from 1 to 5 (×1016)e/cm2. Hall and magnetoresistivity measurement techniques were used to determine irradiation induced changes. The point defect coalescence was assumed to describe the behavior of the electrical parameters.

Fabrication and characterization of P–N dual acceptor doped p-type ZnO thin films

P and N dual-acceptor doped p-type zinc oxide (ZnO:(P, N)) films have been realized by radio frequency (rf) magnetron sputtering and post-annealing techniques. The X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS) and the Hall measurement techniques were employed to investigate the structural and the electrical properties in detail. Results indicated the electrical properties of the ZnO:(P, N) films were extremely sensitive to the annealing temperature and the conduction type could be changed dramatically from n-type to p-type, and finally changed to weak p-type in a range from 650°C to 850°C. The p-type ZnO:(P, N) film with the lower resistivity of 3.98Ωcm, a hole concentration and Hall mobility of 1.16×1018cm−3 and 1.35cm2/Vs, respectively, was obtained at an optimal annealing temperature of 800°C. The p-type conduction behavior of the ZnO:(P, N) film was confirmed by the rectifying I–V characteristics of the p-ZnO:(P, N)/n-ZnO homojunction. The chemical bonding states of P and N doped in ZnO:(P, N) film were examined by XPS analysis.