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Novel combined instrumentation for laser-induced breakdown spectroscopy and Raman spectroscopy for the <i>in situ</i> atomic and molecular analysis of minerals
摘要： An instrument combining laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy was developed for the in situ atomic and molecular composition analysis of minerals. The apparatus consists of an optical system, a sample chamber, a spectrometer for Raman and another for LIBS, as well as a control system equipped with laboratory-written software. Gypsum, calcite, prehnite, pearl, lazurite, and several mixtures of NaBr and CaCO3 were selected as samples for evaluation of the performance of the instrument. Sulfate, carbonate, silicate, and crystalline water were identified and different structures of CaCO3 were clearly distinguished by the use of a Gaussian fit. The limit of detection for CaCO3 in a NaBr mixture was 5.7 mg/g by Raman. LIBS was employed to determine calcium, magnesium, iron, sodium, aluminum, and carbon with the newly developed system. The limits of detection obtained for Ca, Na, and C were 90.2 lg/g, 84.6 lg/g, and 2.5 mg/g, respectively. The experimental results from commercial Raman spectroscopy instruments were used to verify and support the measurements from this novel instrument.
关键词： Instrumentation,Raman spectroscopy,laser-induced breakdown spectroscopy (LIBS),mineral,LIBRAS
更新于2025-11-25 10:30:42
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Effect of K2O addition on glass structure, complex impedance and energy storage density of NaNbO3 based glass-ceramics
摘要： (40-x)Na2O-xK2O-40Nb2O5-20SiO2 (x=0, 5, 10, 15mol%) glass-ceramics are synthesized by traditional melts method. The glass-ceramics are tested by X-ray diffraction (XRD) techniques, and NaNbO3 as major phase led a high permittivity. A microstructure with nanoscale grains enclosed by glass phase is observed by scanning electron microscope (SEM). With the increase of content of K2O, a relaxed glass network structure is obtained, and more kinds of phase are formed. Permittivity comes to 174 approximately when x=5mol%. In addition, the activation energy (Ea) of residual glass phase for Na2O-K2O-Nb2O5-SiO2 glass-ceramics firstly increase then decrease. Breakdown strength (BDS) of all samples increase and then decrease with the increase of content of K2O, and maximum BDS is obtained when x=10mol%. And maximum theoretical energy density is 1.43J/cm3 when x=5mol%.
关键词： breakdown strength,glass network structure,Na2O-K2O-Nb2O5-SiO2 glass-ceramics
更新于2025-11-14 17:28:48
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High Breakdown Strength Schottky Diodes Made from Electrodeposited ZnO for Power Electronics Applications
摘要： The synthesis of ZnO films by optimized electrodeposition led to the achievement of a critical electric field of 800 kV/cm. This value, which is 2 to 3 times higher than in monocrystalline silicon, was derived from a vertical Schottky diode application of columnar-structured ZnO films electrodeposited on platinum. The device exhibited a free carrier concentration of 2.5 × 10^15 cm^-3, a rectification ratio of 3 × 10^8 and an ideality factor of 1.10, a value uncommonly obtained in solution-processed ZnO. High breakdown strength and high thickness capability make this environment-friendly process a serious option for power electronics and energy-harvesting.
关键词： breakdown voltage,electrodeposition,zinc oxide,critical electric field,solution-processed,Schottky diode,power diode,ideality factor
更新于2025-09-23 15:23:52
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Vertical GaN Schottky barrier diodes on Ge-doped free-standing GaN substrates
摘要： Vertical GaN Schottky barrier diodes (SBDs) were fabricated on Ge-doped free-standing GaN substrates grown by hydride vapor phase epitaxy. Detailed material characterization was performed, and the results indicate the superiority of Ge doping in the GaN, which contributed to the SBDs with lower stress, fewer defects and higher quality. Based on the capacitance-voltage and currentevoltage measurements performed, SBDs achieved together with a low turn-on voltage Von (0.71e0.74 V), high current Ion/Ioff ratio (3.9 (cid:1) 107e2.9 (cid:1) 108), high Schottky barrier height (0.96e0.99 eV), and high breakdown voltage Vb (802 V for a 100 mm diameter). This shows that vertical GaN SBDs on the Ge-doped substrates are promising candidates for high power applications.
关键词： GaN device,Vertical SBDs,Low turn-on voltage,Ge-doped GaN substrates,High breakdown voltage
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Cuenca, Ecuador (2018.10.15-2018.10.19)] 2018 IEEE Third Ecuador Technical Chapters Meeting (ETCM) - Reliability in GaN-based devices for power applications
摘要： This paper analyzes two important reliability issues in AlGaN/GaN devices: positive bias temperature instability (PBTI) and time-dependent dielectric breakdown (TDDB). The summarized results of our previous PBTI studies in MOS-HEMTs show that the threshold voltage degradation in devices with SiO2 as gate dielectric is characterized by a universal decreasing behavior of the trapping rate parameter and is ascribed to charge trapping in the SiO2 and at the SiO2/GaN interface. On the contrary, the degradation observed in Al2O3- and AlN/Al2O3-gate stacks is mainly attributed to charge capture in the pre-existing dielectric traps with a negligible interface state generation. Additionally, the insertion of a thin AlN layer impacts on the device reliability because larger trap density, faster charge trapping, wider trap energy distribution and slower charge release are observed compared with devices without this layer. The dielectric importance of GaN-based devices has been also investigated in Schottky Barrier Diodes (SBDs) with a gated edge termination (GET). Our recent TDDB results indicate a narrower Weibull distribution, and a longer time to failure in devices with a double GET layer structure and with a thick passivation layer (2 GET-THICK) than in single GET devices with a thin passivation (1 GET-THIN). Therefore, the former structure is more suitable for high-power and high-temperature applications.
关键词： TDDB,AlGaN/GaN SBD,trapping,de-trapping,reliability,PBTI,breakdown voltage,GET,MOS-HEMT
更新于2025-09-23 15:23:52
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Influence of GaN- and Si?N?-Passivation Layers on the Performance of AlGaN/GaN Diodes With a Gated Edge Termination
摘要： This paper analyses the influence of the GaN and Si3N4 passivation (or 'cap') layer on the top of the AlGaN barrier layer on the performance and reliability of Schottky barrier diodes with a gated edge termination (GET-SBDs). Both GaN cap and Si3N4 cap devices show similar dc characteristics but a higher density of traps at the SiO2/GaN interface or/and an increase of the total dielectric constant in the access region result in higher RON-dispersion in GaN cap devices. The leakage current at medium/low temperatures in both types of devices shows two low-voltage-independent activation energies, suggesting thermionic and field-emission processes to be responsible for the conduction. Furthermore, a voltage-dependent activation energy in the high-temperature range occurs from low voltages in the GaN cap devices and limits their breakdown voltage (VBD). Time-dependent dielectric breakdown measurements show a tighter distribution in Si3N4 cap devices (Weibull slope β = 3.3) compared to GaN cap devices (β = 1.8). Additional measurements in plasma-enhanced atomic layer deposition (PEALD)-Si3N4 capacitors with different cap layers and TCAD simulations show an electric field distribution with a strong peak within the PEALD-Si3N4 dielectric at the GET corner, which could accelerate the formation of a percolation path and provoke the device breakdown in GaN cap SBDs even at low-stress voltages.
关键词： Si3N4 cap,GaN cap,AlGaN/GaN Schottky diode,reliability,breakdown voltage,passivation layer,off-state,Activation energy
更新于2025-09-23 15:23:52
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Performance analysis of a novel trench SOI LDMOS with centrosymmetric double vertical field plates
摘要： A novel trench SOI LDMOS with centrosymmetric double vertical field plates structure (CDVFPT SOI LDMOS) is proposed in this paper. The 2-D device simulator MEDICI is used to investigate the characteristics of the proposed structure. Compared with the conventional trench SOI LDMOS (CT SOI LDMOS), the optimized device shows an obvious reduction in the specific on-resistance (Ron,sp) when its breakdown voltage (BV) is enhanced due to the introduction of centrosymmetric double vertical field plates structure. And when compared to previous device with floating vertical field plate trench SOI LDMOS (FVFPT SOI LDMOS), the overall performance of CDVFPT SOI LDMOS is also promoted. According to the simulation results, compared to a CT SOI LDMOS, the BV of CDVFPT SOI LDMOS increases from 188 V to 234 V. The Ron,sp, however, decreases from 2.30 mΩ·cm2 to 1.24 mΩ·cm2. In addition, the maximum lattice temperature at 1 mW/μm2 is slightly reduced.
关键词： Power MOSFET,Specific on-resistance,Vertical field plate,Breakdown voltage
更新于2025-09-23 15:23:52
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The Study of Electroluminescence and Reliability of Polyimide Films in High DC Fields
摘要： Electroluminescence (EL) intensity of the polyimide (PI) films was tested under dc high electric field by home-made experimental device. The results showed that the EL intensity of PI films increased along with the electric field. EL intensity is approximately to background intensity when the electric-field intensity was less than 2.00 MV/cm. EL intensity increases along with increasing the electric field when electric-field intensity greater than 2.00 MV/cm. When electric-field at 2.80 MV/cm, EL intensity increasing strongly suggests that the excitation process related to hot electrons accelerated by the field approaching a critical threshold. Meanwhile, this work elaborates a method to deal with identical samples get different experimental data by using Weibull distribution method, and the concept of the reliability was presented. The nine groups of EL experimental data were analyzed, and the result showed that the lifetime of mid-value (t = 164.9 min). Mid-value of the breakdown field is E = 2.76 MV/cm.
关键词： reliability,breakdown,Weibull distribution,electroluminescence,PI films
更新于2025-09-23 15:23:52
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Impact of strained silicon on the device performance of a bipolar charge plasma transistor
摘要： In this manuscript we analyze a unique approach to improve the performance of the bipolar charge plasma transistor (BCPT) by introducing a strained Si/SixGe1?x layer as the active device region. For charge plasma realization different metal work-function electrodes are used to induce n+ and p+ regions on undoped strained silicon-on-insulator (sSOI or SixGe1?x) to realize emitter, base, and collector regions of the BCPT. Here, by using a calibrated 2-D TCAD simulation the impact of a Si mole fraction x (in SixGe1?x) on device performance metrics is investigated. The analysis demonstrates the band gap lowering with decreasing Si content or effective strain on the Si layer, and its subsequent advantages. This work reports a significant improvement in current gain, cutoff frequency, and lower collector breakdown voltage (BVCEO) for the proposed structure over the conventional device. The effect of varying temperature on the strained Si layer and its implications on the device performance is also investigated. The analysis demonstrates a fair device-level understanding and exhibits the immense potential of the SixGe1?x material as the device layer. In addition to this, using extensive 2-D mixed-mode TCAD simulation, a considerable improvement in switching transient times are also observed compared to its conventional counterpart.
关键词： bipolar charge plasma transistor (BCPT),mole fraction,cutoff frequency (fT),current gain (β),collector breakdown voltage (BVCEO),strained Si layer,band gap lowering
更新于2025-09-23 15:23:52
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Threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes with high temperature stability
摘要： This letter reports the observation of threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes. This mechanism was ascribed to the conductive path formed by traps in the insulating layer at the regrowth interface after soft breakdown. The device can reliably switch more than 1000 cycles at both room temperature and 300 oC with small fluctuation on the set and reset voltage. The set voltage increased with the increasing temperature due to the enhanced thermal detrapping effect that made it harder to form conductive path at high temperatures. Besides, the device showed memory behaviors when the reset voltage was higher than 4.4 V. This work can serve as important references to further developing GaN-based memory devices and integrated circuits.
关键词： memory,breakdown,wide bandgap semiconductor,threshold switching,p-n diodes,Gallium nitride
更新于2025-09-23 15:22:29