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Improvement of charge transport for hydrothermally synthesized Cd0.8Fe0.2S over co-precipitation method: A comparative study of structural, optical and magnetic properties
摘要： Here, we have elucidated the structural, optical, magnetic and electrical properties of Cd0.8Fe0.2S which is considered as diluted magnetic semiconductor (DMS). Cd0.8Fe0.2S materials were synthesized using co-precipitation (compound 1) and hydrothermal (compound 2) method. The particle size and the polycrystalline phase of the synthesized materials are significantly influenced by the synthesis procedures. Presence of anti-ferromagnetic coupling confirms the magnetic behavior of materials. The current-voltage (I-V) characteristics exhibit lower barrier height for the device based on compound 2 (0.59 eV) than the other device (0.64 eV). Furthermore, the 19 times enhanced mobility and lesser density of states near the Fermi level for the Al/compound 2/ITO configured device is enlightened by the space charge conduction mechanism. But, the interface resistances of the devices cannot be distinguished by the I-V characteristics. Therefore, we have tackled the problem by simulating the Nyquist plots obtained from impedance spectroscopy. We have fitted the Nyquist plots with the appropriate equivalent circuit and explained the mechanism of charge transport through the Schottky interface. The higher dc conductivity and lower relaxation time of diode fabricated by compound 2 confirm the outcomes obtained from I-V characteristics. The effect of particle size on charge transport was also analyzed.
关键词： Schottky diode characteristics,Diluted magnetic semiconductor,Chemical synthesis,Impedance spectroscopy
更新于2025-09-10 09:29:36
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Theoretical Study of the Magneto-Thermoelectric Effect in Doped Semiconductor Superlattices under the Influence of an Electromagnetic Wave by Using a Quantum Kinetic Equation
摘要： By using a quantum kinetic equation for electrons, we studied magneto - thermoelectric effects in the doped semiconductor superlattice (DSSL) under the influence of electromagnetic waves (EMW). In case of the electron - acoustic phonon interaction, we have also figured out analytical expressions of the Ettingshausen coefficient (EC) in DSSL. These expressions are quite different from those which were obtained in the case of bulk semiconductors. The results are numerically calculated for the GaAs:Be/ GaAs:Si DSSL; we found that the EC depends on the characteristic parameters of EMW, temperature and the characteristic parameters of DSSL. The results are consistent with recently experimental observations but the EC is different from that in the bulk semiconductors or bismuth. In addition, the impact of the EMW on the Ettingshausen effect was also discovered. These are latest results which have been studied in terms of Ettingshausen effect in DSSL.
关键词： Semiconductor Superlattices,Doped Superlattices,Acoustomagnetoelectric field,Kinetic equation method
更新于2025-09-10 09:29:36
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Mechanisms of humidity sensing on a CdS nanoparticle coated paper sensor
摘要： A combined experimental and computational study is presented to identify the salient features of the adsorption of water molecules from a humid gas on the surface of a film of cadmium sulfide nanoparticles (CdSNPs). It is well known that, apart from showing exquisite optical and electrical properties, CdSNPs are also capable of adsorbing humidity from the gas or vapors. In the present study, we explore the variation in the electrical conductivity of a film of CdSNPs with the variation in the flowrate of a humid gas, which can lead to the development of a humidity or a flowrate sensor. The computational study shows that the increase in the concentration of adsorbed molecules with the enhancement in the flowrate of the humid gas can lead to a variation in the electrical conductance of the CdSNP film. The adsorption of water molecules on the sensor is correlated with the band bending of the CdSNP film owing to the ionization of the adsorbed molecules on the sensor surface. The electrical conductance of the sensor is found to vary in the range of 55–95% when the flowrate of the humid gas is varied from ～200 to 600 L/min, at a relative humidity of ～97%. A logarithmic dependence of the flowrate of the humid gas with the concentration of the water molecules adsorbed on the film surface is found to explain the experimental observations.
关键词： Humidity,Nanoparticles,Sensor,Adsorption,Semiconductor
更新于2025-09-10 09:29:36
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From EBIC images to qualitative minority carrier diffusion length maps
摘要： A novel method is presented with the aim to perform minority carrier di?usion length map on cross-sectional samples. The method is based on one Electron-Beam Induced Current (EBIC) acquisition and on the analyze of the EBIC signal slope variation on each scanned points. This method is applied on a pinned photodiode array realized on a low doped silicon epitaxy, and the electron di?usion length map which is extracted is in good accordance with our expectation taking into account the doping distribution of the device. A TCAD simulation also con?rms quantitatively the measured di?usion length map. Advantages and drawbacks of this method are discussed in this study.
关键词： CMOS image sensors,CMOS,Scanning electron microscopy (SEM),Simulation,Electron-beam-induced current (EBIC),Deep submicron process,Solid-state image sensor,Semiconductor material measurements
更新于2025-09-10 09:29:36
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Modified qHAADF method for atomic column-by-column compositional quantification of semiconductor heterostructures
摘要： The qHAADF method allows the quanti?cation of the composition at atomic column resolution in semiconductor materials by comparing the HAADF-STEM intensities between a region of interest to a region of the material of known composition. However, the application of this qHAADF approach requires both regions to be differentiable and included in the same micrograph at close proximity. This limits the application of this approach to certain materials and magni?cations where this requirement is ful?lled. In this work, we extend the qHAADF method to analyses where the reference region is imaged in a separate micrograph. The validity of this modi?ed method is proved by comparison to the original qHAADF approach using HAADF-STEM simulated images of the semiconductor heterostructure InSb/InAs. Additionally, the methods are applied successfully to experimental images both of a simple InSb/InAs interface and of a complex InSb/GaSb heterostructure, justifying the signi?cance of the modi?ed method over the original method.
关键词： compositional quanti?cation,qHAADF method,HAADF-STEM,semiconductor heterostructures,atomic column resolution
更新于2025-09-10 09:29:36
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Optimization of InP DHBT stacked-transistors for millimeter-wave power amplifiers
摘要： In this paper, we report the analysis, design, and implementation of stacked transistors for power amplifiers realized on InP Double Heterojunction Bipolar Transistors (DHBTs) technology. A theoretical analysis based on the interstage matching between all the single transistors has been developed starting from the small-signal equivalent circuit. The analysis has been extended by including large-signal effects and layout-related limitations. An evaluation of the maximum number of transistors for positive incremental power and gain is also carried out. To validate the analysis, E-band three- and four-stacked InP DHBT matched power cells have been realized for the first time as monolithic microwave integrated circuits (MMICs). For the three-stacked transistor, a small-signal gain of 8.3 dB, a saturated output power of 15 dBm, and a peak power added efficiency (PAE) of 5.2% have been obtained at 81 GHz. At the same frequency, the four-stacked transistor achieves a small-signal gain of 11.5 dB, a saturated output power of 14.9 dBm and a peak PAE of 3.8%. A four-way combined three-stacked MMIC power amplifier has been implemented as well. It exhibits a linear gain of 8.1 dB, a saturated output power higher than 18 dBm, and a PAE higher than 3% at 84 GHz.
关键词： Power amplifiers,semiconductor devices and IC-technologies,stacked-transistor
更新于2025-09-10 09:29:36
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Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing
摘要： InAs crystals are emerging materials for various devices like radio-frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al2O3/InAs interfaces, pre-oxidized differently, with synchrotron hard x-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for well-embedded InAs interfaces (12 nm Al2O3) to avoid, in particular, effects of a significant potential change at the vacuum-solid interface. High-resolution As 3d spectra reveal that the Al2O3/InAs interface, which was sputter-cleaned before ALD, includes +1.0 eV shift, whereas As 3d of the pre-oxidized (3×1)-O interface exhibits a shift of -0.51 eV. The measurements also indicate that an As2O3 type structure is not crucial in controlling defect densities. Regarding In 4d measurements, the sputtered InAs interface includes only a +0.29 eV shift, while the In 4d shift around -0.3 eV is found to be inherent for the crystalline oxidized interfaces. Thus, the negative shifts, which have been usually associated with dangling bonds, are not necessarily an indication of such point defects as previously expected. In contrast, the negative shifts can arise from bonding with O atoms. Therefore, specific care should be directed in determining the bulk-component positions in photoelectron studies. Finally, we present an approach to transfer the InAs oxidation results to a device process of high electron mobility transistors (HEMT) using an As-rich III-V surface and In deposition. The approach is found to decrease a gate leakage current of HEMT without losing the gate controllability.
关键词： synchrotron,oxidation,atomic layer deposition,III-V semiconductor,photoelectron,InAs
更新于2025-09-10 09:29:36
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Cryogenic Characterization of 22nm FDSOI CMOS Technology for Quantum Computing ICs
摘要： An approach is proposed to realize large-scale, “high-temperature” and high-fidelity quantum computing ICs based on single- and multiple coupled quantum-dot electron- and hole-spin qubits monolithically integrated with the mm-wave spin manipulation and readout circuitry technology. Measurements of minimum-size 6nmx20nmx80nm Si-channel n-MOSFETs (electron-spin qubit), SiGe-channel p-MOSFETs (hole-spin qubit), and double quantum-dot complementary qubits reveal strong quantum effects in the subthreshold region at 2 K, characteristic of resonant tunneling in a quantum dot. S-parameter measurements of a transimpedance amplifier (TIA) for spin readout show improved performance from 300 K to 2 K. Finally, the qubit-with-TIA circuit has 50Ω output impedance, 78dBΩ transimpedance gain with unity-gain bandwidth of 70 GHz and consumes 3.1 mW.
关键词： CMOS,silicon-on-insulator,quantum information processing,radio frequency,monolithic integrated circuits,semiconductor quantum dots,silicon,cryogenics
更新于2025-09-10 09:29:36
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A Material for Difference-Frequency Generation of Terahertz Radiation
摘要： The possibility of efficient difference-frequency generation of terahertz radiation in a metamaterial representing a structure consisting of alternating layers of a semiconductor materials exhibiting intrinsic or metallic conductivity that can be grown by epitaxial methods is investigated theoretically.
关键词： terahertz radiation,metamaterial,epitaxial methods,difference-frequency generation,semiconductor
更新于2025-09-10 09:29:36
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Detectors of Circularly Polarized Radiation Based on Semiconductor Heterostructures with a CoPt Schottky Barrier
摘要： In this paper, we showed the possibility of practical realization of circularly polarized radiation detectors based on a planar photoresistor using the effect of magnetocircular dichroism in the CoPt layer, as well as based on structures using the spin filtration by the CoPt layer of photogenerated spin-polarized charge carriers. The spin filtration process is established to allow increasing the detection efficiency of up to 1.3%.
关键词： semiconductor heterostructures,spin filtration,magnetocircular dichroism,circularly polarized radiation detectors,CoPt layer
更新于2025-09-10 09:29:36