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An Overview of the Ultrawide Bandgap Ga2O3 Semiconductor-Based Schottky Barrier Diode for Power Electronics Application
摘要： Gallium oxide (Ga2O3) is a new semiconductor material which has the advantage of ultrawide bandgap, high breakdown electric field, and large Baliga’s figure of merit (BFOM), so it is a promising candidate for the next-generation high-power devices including Schottky barrier diode (SBD). In this paper, the basic physical properties of Ga2O3 semiconductor have been analyzed. And the recent investigations on the Ga2O3-based SBD have been reviewed. Meanwhile, various methods for improving the performances including breakdown voltage and on-resistance have been summarized and compared. Finally, the prospect of Ga2O3-based SBD for power electronics application has been analyzed.
关键词： Breakdown electric field,Baliga’s figure of merit,On-resistance,Ultrawide bandgap semiconductor,Gallium oxide (Ga2O3),Power device,Schottky barrier diode (SBD)
更新于2025-09-23 15:22:29
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Copper electrodeposition on silicon electrodes
摘要： A two-step process is reported for the electrochemical deposition of copper layers on n-type silicon substrates using an acidic copper sulphate solution without addition of additives and no light assistance. Metal layers were generated on electrodes with different crystal orientations. The process consists of a combination of two very common techniques: chronoamperometry and pulse plating. The former technique is applied to obtain an instantaneous nucleation on the working electrode. Therefore, a large amount of metal nuclei is formed on the substrate before the pulse technique starts. The latter is, then, used to grow the particles previously generated and form a homogeneous metal layer with full coverage onto the semiconductor electrodes. The potential magnitudes are carefully chosen in line with energy levels observed at the semiconductor-electrolyte interface and were also calculated in this work.
关键词： silicon coating,seedless electroplating,copper plating,semiconductor-electrolyte interface,pulse plating
更新于2025-09-23 15:22:29
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Runaway electrons diagnostics using segmented semiconductor detectors
摘要： A novel application of strip and pixel silicon radiation detectors for study and characterization of run-away electron events in tokamaks is presented. Main goal was to monitor runaway electrons both directly and indirectly. The strip detector was placed inside the tokamak vacuum chamber in order to monitor the run-away electrons directly. Whereas the pixel detector was placed outside the tokamak chamber behind a pin hole for monitoring the run-away electrons indirectly via radiation produce by interaction of the electrons with the plasma facing material. Results obtained using the silicon detectors are compared with already existing diagnostic methods consisting of scintillation devices detecting X-rays and photo-neutrons, providing the same results in the observable comparisons. Tests with the pixel detector proved that the pinhole camera is able to extract spatial information of interaction point (a place where the runaway electrons hit on the facing material) and the strip detectors indicate presence of additional signal from throughout the discharge. The performed experiments are innovative, illustrating possible development of new and easy to use diagnostic method.
关键词： Runaway electrons,Tokamaks,Semiconductor detectors
更新于2025-09-23 15:22:29
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Quantum well photoelastic comb for ultra-high frequency cavity optomechanics
摘要： Optomechanical devices operated at their quantum limit open novel perspectives for the ultrasensitive determination of mass and displacement, and also in the broader field of quantum technologies. The access to higher frequencies implies operation at higher temperatures and stronger immunity to environmental noise. We propose and demonstrate here a new concept of quantum well photoelastic comb for the efficient electrostrictive coupling of light to optomechanical resonances at hundreds of GHz in semiconductor hybrid resonators. A purposely designed ultra-high resolution Raman spectroscopy set-up is exploited to evidence the transfer of spectral weight from the mode at 60 GHz to modes at 190–230 GHz, corresponding to the 8th and 10th overtone of the fundamental breathing mode of the light-sound cavities. The coupling to mechanical frequencies two orders of magnitude larger than alternative approaches is attained without reduction of the optomechanical constant g0. The wavelength dependence of the optomechanical coupling further proves the role of resonant photoelastic interaction, highlighting the potentiality to access strong-coupling regimes. The experimental results show that electrostrictive forces allow for the design of devices optimized to selectively couple to specific mechanical modes. Our proposal opens up exciting opportunities towards the implementation of novel approaches applicable in quantum and ultra-high frequency information technologies.
关键词： semiconductor microcavity,Raman scattering,optomechanics
更新于2025-09-23 15:22:29
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On-chip Optical Vector Quadrature De-multiplexer Proposal for QAM De-aggregation by Single Bi-directional SOA-based Phase-sensitive Amplifier
摘要： In this paper, a simple optical vector quadrature de-multiplexer (QD) scheme is proposed for de-aggregating input 10 Gbaud 16/32/64 quadrature amplitude modulation (QAM) signals into two pulse amplitude modulation (PAM) streams. The proposed QD is based on a single bi-directional degenerate phase-sensitive amplifier (PSA), where the wavelength and the polarization status of the extracted in-phase and quadrature components stay the same as the input signal. Since the proposed QD is realized using PSA based on semiconductor optical amplifier (SOA), it is also possible to realize an on-chip QD system, providing an integrated platform for optical signal processing. Through numerical simulation, the transfer characteristics of the proposed QD system show that the SOA-based PSA has a high phase-sensitive gain extinction ratio of 44.1 dB. The constellations, error vector magnitudes (EVMs), and bit-error rates (BERs) of the data streams after the de-aggregation are numerically investigated to verify the proposed QD scheme. For the 10 Gbaud 16/32/64 QAM signals with an input optical signal-to-noise ratio (OSNR) of 25 dB, the de-aggregated PAM4/PAM6/PAM8 signals show 6.1, 5.6, and 8.2 dB receiver OSNR improvements at the BER of 10?3, respectively. Also, to optimize the performance of the subsystem, the BER performance dependence on the phase difference between two arms in the subsystem is also examined. The simulation results reveal that the proposed QD can accomplish the function of optical vector de-aggregation well for the high-level QAM signals. The proposed QD can be applied to information de-aggregation, format conversion, and direct detection for optical vector signals, which may have great potential values for the flexible optical networks.
关键词： Optical fiber communication,semiconductor optical amplifiers,nonlinear optical devices,optical signal processing
更新于2025-09-23 15:22:29
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Investigation of Trap-Induced Threshold Voltage Instability in GaN-on-Si MISHEMTs
摘要： It is shown that an EC–0.90 eV trap in commercial AlGaN/GaN MISHEMTs grown on a Si (111) substrate is responsible for a ?1.8-V threshold voltage (VT) instability using a combination of defect spectroscopy and double-pulsed current–voltage measurements. The EC ? 0.90 eV trap is located in the GaN buffer and is emptied by high drain biases in pinch-off, which raises the trap above the Fermi level in the GaN buffer. This trap also exhibits both fast and slow recovery processes that are explained by the availability of free electrons throughout the depth of the GaN buffer and the trapping process that depletes the free electron concentration. TCAD modeling is used to demonstrate this process and also to show why there is not a significant increase in buffer leakage current after the large negative VT shift due to this trap. This demonstrates that optimizing buffer designs are critical for ideal device performance.
关键词： deep-level transient spectroscopy (DLTS),isothermal,GaN-on-Si,threshold voltage instability,metal-insulator-semiconductor high electron mobility transistors (MISHEMTs),Capture process,trap
更新于2025-09-23 15:22:29
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An Electrical Analysis of a Metal-Interlayer-Semiconductor Structure on High-Quality Si <sub/> 1? <i>x</i> </sub> Ge <sub/><i>x</i> </sub> Films for Non-Alloyed Ohmic Contact
摘要： In this paper, we have investigated the effect of a metal-interlayer-semiconductor (MIS) structure on intrinsic silicon-germanium (SiGe) film which is epitaxially grown by ultra-high vacuum chemical vapor deposition (UHV-CVD). Ultra-thin dielectric materials can alleviate Fermi-level pinning at the metal/Si1?xGex contact region by preventing penetration into the Si1?xGex of metal-induced gap states (MIGS) from the metal surface. The electrical properties which are the back-to-back current density and specific contact resistivity of the Ti/TiO2/Si1?xGex structure improve at the TiO2 interlayer thickness of 0.5 nm for all kinds of Si1?xGex film with various levels of germanium (Ge) concentration. The case of Si0.7Ge0.3 film, the specific contact resistivity of a Ti/TiO2(0.5 nm)/Si0.7Ge0.3 structure is reduced 80-fold compared to that of a Ti/Si0.7Ge0.3 structure. The effect of the MIS structure has been well demonstrated on Si1?xGex film, and as a result this structure is suggested as a novel source/drain (S/D) contact scheme for advanced Si1?xGex complementary metal-oxide-semiconductor (CMOS) technology.
关键词： Epitaxial Growth,Metal-Interlayer-Semiconductor,Source/Drain Contact,Silicon-Germanium,Fermi-Level Pinning,Specific Contact Resistivity
更新于2025-09-23 15:22:29
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Chiral semiconductor nanorod heterostructures with high photocatalysis activity
摘要： Chiral semiconductor nanorods and their heterostructures have attracted intense attention. In this work, it was shown that chiral amino acids on CdSe@CdS semiconductor nanorods (SNR) displayed circular dichroism bands (CD, 200–480 nm). Longer SNRs were found to induce stronger CD intensities, while an increase in the SNR diameter led to a clear CD band redshift. Multi-site post-growth of platinum (Pt) and gold (Au) further enhanced the CD intensity and induced CD band transitions. Electromagnetic calculations revealed that the metal post-growth gave rise to a strong electromagnetic field enhancement, with Pt inducing a stronger enhancement than Au. The optimized chiral multi-sites platinum on SNR displayed higher photocatalytic activities manifested that the deposited metal endowed energy transfer and enhanced the separation of photo-excited electrons and holes. These findings demonstrated that the multi-sites deposited metal provided a method to produce strong optical activity of nanostructures by adjusting the morphology of the semiconductor nanorod.
关键词： circular dichroism,metal growth,heterostructure,semiconductor nanorods
更新于2025-09-23 15:22:29
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Effects of Spatial Dispersion in Symmetric and Asymmetric Semiconductor Quantum Wells
摘要： Effects of spatial dispersion in quantum wells are discovered and investigated in detail in reflection experiments. We studied oblique incidence of pure s and p polarized light which has been reflected elliptically polarized. The polarization degree of the reflected light is governed by the in-plane photon momentum which is the distinctive feature of the spatial dispersion effects. The effects of spatial dispersion are allowed by symmetry in inversion-asymmetric systems only. Therefore we investigated bulk-inversion asymmetric ZnSe/ZnMgSSe and structure-asymmetric GaAs/AlGaAs and CdZnTe/CdTe/CdMgTe quantum wells. We studied the reflected light polarization state in the vicinity of the heavy- and light-exciton resonances where the spatial dispersion effects are resonantly enhanced.
关键词： semiconductor quantum wells,light polarization conversion,excitons,spatial dispersion
更新于2025-09-23 15:22:29
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Ferromagnetism and Carrier Transport in n-type Diluted Magnetic Semiconductors Ge0.96?xBixFe0.04Te Thin Film
摘要： The structural, Hall effect, electronic transport, and magnetic properties of Ge0.96?xBixFe0.04Te epitaxial thin film as prepared by pulsed laser deposition technique were reported. X-ray diffraction patterns including linear scans and phi scans confirmed that all films are high quality epitaxy and crystallinity. With the substitution of high valence Bi for Ge element, we found that the previous carriers of hole were changed to electron, which was testified by the negative slopes obtained from the measurements of Hall effect under different temperatures. The electronic transports show a typical semiconductor behavior and can be understood by the small polaron hopping model because the lattice distortions increase the electron-phonon interaction. An obvious ferromagnetic properties occur in the high Bi-doping Ge0.64Bi0.32Fe0.04Te rather than in that with low Bi-doping concentration, indicating that the ferromagnetic establishment is entirely dependent on carrier’s transmissions. The first-principles calculation performed on this system also reveals that the ferromagnetic state exactly exists in the present n-type diluted magnetic semiconductors with Bi co-dopants.
关键词： N-type semiconductor,Ferromagnetism,Diluted magnetic semiconductors
更新于2025-09-23 15:22:29