Papers by Keyword: Hall Effect

Abstract: Cu₃SnS₄ films were grown on glass substrates via method of spin coating, followed by annealing at 550 °C in a furnace under H₂S:Ar (1:9) sulfur rates of 30 and 40 sccm for 15, 30, and 60 minutes. The effect of the sulfur rate and annealing time on the structural, morphological, and optical behaviors of the samples was systematically investigated using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), photoluminescence (PL), Hall effect, and UV-Vis spectroscopy. The XRD patterns revealed that all the Cu₃SnS₄ samples had a polycrystalline structure. The crystallite size, dislocation density, interplaner distance, micro-strain, and crystallite number of the Cu₃SnS₄ samples were calculated from the XRD spectra. Among all the samples, the CTS sample annealed for 15 minutes under a 30 sccm H₂S:Ar (1:9) gas flow showed the best crystalline structure. The surface morphology of the samples showed spherical micro-crystal formations. Analysis of the Cu₃SnS₄ samples indicated that the surfaces were composed of valley and peak regions. The valley regions appeared relatively smooth, while the peak regions displayed a crystal structure with specific orientations. When examining the energy band gap values, it is observed that the energy band gap of the films increases significantly with the increase in sulfur flow rate. PL analysis revealed emission peaks at approximately 1.41 eV and 1.80 eV, along with broad emission bands at 549 nm, 567 nm, 689.42 nm, and 882.6 nm. An increase in sulfur content led to a reduction in peak intensity, which is attributed to conduction band fluctuations and the formation of structural defects. The carrier concentration of the samples is found to be on the order of 10¹⁷ cm⁻³ and 10¹⁸ cm⁻³, which is more appropriate for thin-film solar cells (TFCSs).

Abstract: This paper is a comparison of the carrier deflection mechanism of a new magnetic sensor structure between the tunneling Field Effect Transistor (TFET) structure and the FinFET structures so-called MAG-TFET and MAG-FinFET.The device relies on carrier deflection from magnetically induced forces. The MAG-TFET current is caused by electron tunneling and drifting through the bulk under gate while the MAG-FinFET current is caused by the drift channel carrier from the inversion layer induced by gate voltages and there is also a bulk current beneath the substrate. The carrier deflection of the device is due to the current in the induced channel and current in the bulk. From the results, carrier deflection in the induced channel is better than in the bulk. The device sensitivity depends on the proportion of these two currents.

Abstract: The deposition of Zinc Sulfide (ZnS) thin films is optimized using a radio-frequency (RF) magnetron sputtering technique with variable RF power to minimize deposition steps and lower the fabrication costs. Room temperature as-deposited film growth optimization is conducted by studying their structural, morphological, optical, and electrical properties. The target power and deposition rate were related by a slope of 0.1648 and a linear correlation coefficient (R) of 0.9893. Only one significant peak for the films in the XRD pattern indicated that the films are of a single crystalline structure. All the deposited thin films exhibited a ZB structure. It is observed that the micro-strain ranged from 36.00x10^-3 to 4.14x10^-3, and that of dislocation density ranged from 6.68 to 0.08 Line/cm². The optical energy band gaps of as-deposited ZnS films at different deposition power were found from 3.31 to 3.37 eV. The average transmittance percentage was increasing from 71.63% to 84.29%, above 400 nm wavelength. The films exhibited n-type conductivity with bulk carrier density in the order of 10¹² cm^-3. The carrier concentration and mobility ranged from 2.84x10¹¹ to 3.98x10¹² cm^-3 and 1.06 to 27.68 cm²/Vs, respectively. The minimum and maximum resistivity of 1.01x10⁴ and 2.52´10⁵ Ω-cm were noted for the film deposited at 90 and 60W power, respectively.

Abstract: In this study, Cu₂FeSnS₄ (CFTS) thin films were deposited on glass substrates at different temperatures of 250, 300, 350, 400, and 450 °C using the chemical pyrolysis technique. This work aimed to study the effect of substrate temperature on film properties. The film's structural properties were obtained via X-ray diffraction, Raman spectroscopy, and Field Emission Scanning Electron Microscopy (FESEM). The UV-Vis spectrum determined the optical properties; and the electrical properties were obtained through observation of the Hall effect. Analysis of XRD pattern showed that the CFTS thin films have a tetragonal structure with a main peak corresponding to the direction (112). Results of Raman spectroscopy displayed a unique peak at 318 cm^-1, suggesting a quaternary compound of CFTS. The FESEM tests confirmed the presence of nanoparticles of various shapes and sizes. The CFTS films have a band gap of 1.77-1.92 eV and an absorption coefficient in the visible spectrum region higher than 10⁴ cm^-1, which confirms their use as an active layer in solar cells. The mea measurements of the Hall effect of the CFTS thin films showed a p-type conductivity for all films, with the maximum charge carrier density and mobility occurring at 400 °C, making them suitable for photovoltaic applications.

Abstract: The study of Hall effect of Kondo semiconductor CeFe₂Al₁₀ is reported as a candidate of thermoelectric material used at low temperatures. Single crystals of CeFe₂Al₁₀ with orthorhombic crystal structure were grown by Al self-flux method. An anisotropy of the Hall effect is clarified by measuring Hall resistance by changing the direction of electrical current, magnetic field, and voltage respect to all the three crystal axes of orthorhombic crystal structure. The Hall effect of CeFe₂Al₁₀ has a strong anisotropy against the direction of magnetic field but weak anisotropy against the directions of current and voltage. The value of carrier concentration indicates that CeFe₂Al₁₀ is matallic, which causes a low performance as a thermoelectric material. In order to improve the value of dimensionless figure of merit, the electrons should be doped to CeFe₂Al₁₀.

Abstract: Resistivity, r (T), and Hall coefficient in weak (B < 1 T) magnetic fields, R (T), are investigated in Ca₂Si and CaSi₂ films at temperatures T between ~ 20 - 300 K. In CaSi₂, r (T) is typical of metals increasing with T within the whole temperature range. On the other hand, the resistivity of Ca₂Si is pertinent of semiconductors. Namely, it is activated below T ~ 200 K, exhibiting different slopes of ln r vs. T ^-1 plots at lower and higher T, and a weak increase between T ~ 200 - 300 K. Both materials demonstrate a complex dependence of R (T), including a change of the sign. Transport properties above have been analyzed assuming two groups of charge carriers, electrons and holes, contributing them.

Abstract: The Cd₃As₂+MnAs composite with 20 mole % of MnAs has been studied complexly in a wide ranges of temperatures, pressures and magnetic fields. Negative magnetic resistance has been found in the sample. This anomalous behavior is considered as a result of changes in tunneling processes due to reduce of distance between magnetic moment of ferromagnetic and structural transitions caused by pressure.

Abstract: This paper studies the aspect ratio (W/L), width (W) per length (L) of semiconductor resistor based on Hall effect current mode for horizontal magnetic field. At low concentration, 10¹⁴ cm^-3, W/L < 1, the length has direct effect to magnetoresistance. The W/L = 1, the large resistor provides magnetioresistance better than small device. The W/L ˃ 1, the width has inversely proportional to magnetoresistance. The %MR(B) is around 1 % at 0.5 T, 1 mA. The long resistor (W/L < 1) can create ΔR in the order of several kilo ohms and several hundred ohms for short resistor (W/L > 1). The contribution factors ρ (L/W) for high ΔR are low concentration and aspect ratio (W/L < 1). The high %MR(B) is contributed by high current density of short structure (W/L > 1). At high concentration 10¹⁷ cm^-3, aspect ratio and magnetoresistance are not sensitive to magnetic field because the Hall effect hardly occurs in high concentration material.

Abstract: Aluminum implanted 4H-SiC often shows an unexpected increase of the free hole density at elevated temperatures in Hall Effect measurements. Here we show that this phenomenon cannot solely be traced down to the Hall scattering factor and the presence of excited acceptor states. It is necessary to assume an additional defect center in the lower half of the band gap with ionization energies higher than that of aluminum to explain this behavior. Therefore, we investigated ion-implanted square van-der-Pauw samples with Hall Effect and complementary SIMS measurements. An analysis of the data using the neutrality equation reveals compensation ratios of 20 % to 90 %, depending on the aluminum concentration and the concentration of the deep defect center of up to 50 % of the doping.

Abstract: This experimental research proposes a contactless silicon-based two-dimensional (2D) Hall sensor capable of simultaneous parallel-and perpendicular-directional magnetic sensing, with a 360° angle measurement. The Hall sensor was of non-symmetrical five-ohmic contact configuration (C1 – C5). In the study, experiments were carried out in three stages. In the first-stage experiment, the current (I) and voltage (V) of the 2D Hall sensor were determined under three schemes: schemes A (C1&C2), B (C2&C5), and C (C3&C4). In the second-stage experiment, the parallel and perpendicular absolute sensitivities of the 2D sensor were examined. Considering the discrepancy between the parallel and perpendicular absolute sensitivities, signal conditioning circuitry was incorporated into the sensor system to compensate, and the rotational angles measured in the final-stage experiment. The results revealed that the I-V curves were dominantly linear, corresponding to Ohm’s law. However, the parallel and perpendicular absolute sensitivities were low and unequal. Thus, signal conditioning circuitry was incorporated into the system to address the discrepancy and improve the performance. Importantly, the 2D Hall sensor exhibited a mere ±3^o discrepancy between the measured and reference rotational angles, given the magnetic flux density of 1000 G, with the hysteresis error of 2.8%. In essence, the proposed contactless silicon-based 2D Hall sensor possesses high potential for high-precision industrial applications.