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oe1(光电查) - 科学论文

197 条数据
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  • Evaluation of Low-Temperature Saturation Velocity in β -(Al?Ga???)?O?/Ga?O? Modulation-Doped Field-Effect Transistors

    摘要： We report on the high-field transport characteristics and saturation velocity in a modulation-doped β-(AlxGa1?x)2O3/Ga2O3 heterostructure. The formation of a 2-D electron gas (2DEG) in the modulation-doped structure was confirmed from the Hall measurements, and the 2DEG channel mobility increased from 143 cm2/V·s at room temperature to 1520 cm2/V·s at 50 K. The high electron mobility at 50 K made it feasible to achieve velocity saturation inside the channel. The saturation velocity was estimated based on both pulsed current–voltage measurements and small-signal radio frequency (RF) measurements. The measured velocity–field profile suggested a saturation velocity above 1.1 × 107 cm/s at 50 K. The small-signal RF characteristics were measured for the fabricated modulation-doped field-effect transistors with a Pt-based Schottky contact. The current gain cutoff frequency (ft) and maximum oscillation frequency (fmax) showed significant increases from 4.0/11.8 GHz at room temperature to 17.4/40.8 GHz at 50 K for the device with gate length of LG = 0.61 μm. The analysis of the low temperature ft based on device simulations indicated a peak velocity of 1.2 × 107 cm/s. The three-terminal off-state breakdown measurement further suggested an average breakdown field of 3.22 MV/cm. The high saturation velocity and high breakdown field in β-Ga2O3 make it a promising candidate for high-power and high-frequency device applications.

    关键词： mobility,β-Ga2O3,modulation-doped field-effect transistor (MODFET),2-D electron gas (2DEG),saturation velocity,high breakdown field

    更新于2025-09-23 15:22:29

  • Effect of short-circuit stress on the degradation of the SiO2 dielectric in SiC power MOSFETs

    摘要： This paper presents the impact of a short-circuit event on the gate reliability in planar SiC MOSFETs, which becomes more critical with increased junction temperature and higher bias voltages. The electrical waveforms indicate that a gate degradation mechanism takes place, showing a large gate leakage current that increases as the gate degrades more and more. A failure analysis has been performed on the degraded SiC MOSFET and then compared to the structure of a new device to identify possible defects/abnormalities. A Focused-Ion Beam cut is performed showing a number of differences in comparison to the new device: (i) cracks between the poly-silicon gate and aluminium source, (ii) metal particles near the source contact, and (iii) alterations in the top surface of the aluminium source. The defects have been correlated with the increase in gate-leakage current and drain-leakage current.

    关键词： Focused-Ion Beam,Short circuit,Gate-oxide breakdown,Gate oxide,Degradation,Defects,Reliability,SiC MOSFET,Failure analysis,SEM

    更新于2025-09-23 15:22:29

  • Gas Breakdown and Discharge Formation in High-Power Impulse Magnetron Sputtering

    摘要： Discharge behaviors of high-power impulse magnetron sputtering with different targets have been investigated. Distinct current–voltage curves and target current waveforms are observed. Breakdown voltage and the maximum target current show a periodic drop with the increase of atomic number in subgroups and periods. The target current density is found to be mainly affected by the secondary electron emission yield. Thus, its magnitude is unable to directly evaluate the ionization degree of sputtered atoms in high-power impulse magnetron sputtering (HiPIMS) process. In this paper, the interactive influence of secondary electron emission, sputter yield, and ionization energy on the ionization degree of sputtered atoms is discussed based on the analysis of the voltage and current characteristics. As a result, targets can be categorized into three sorts according to the ionization degree: 1) low ionization degree targets, such as Ag and C less than 10%; 2) intermediate ionization degree targets like Cr and Cu with 55% and 35%; 3) Ti, Zr, and Mo targets with the second ionization processes. These results provide institutive operation ranges for the state-of-the-art HiPIMS applications.

    关键词： optical emission spectroscopy (OES),ionization degree,Current waveform,gas breakdown,high-power impulse magnetron sputtering (HiPIMS)

    更新于2025-09-23 15:22:29

  • 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

  • [IEEE 2017 9th IEEE-GCC Conference and Exhibition (GCCCE) - Manama, Bahrain (2017.5.8-2017.5.11)] 2017 9th IEEE-GCC Conference and Exhibition (GCCCE) - Polarization Engineered Enhancement Mode High Breakdown Voltage GaN CAVET

    摘要： In this work we propose and simulate a polarization engineered enhancement mode current aperture vertical electron transistor (P-CAVET). The novelty of the proposed structure lies in using polarization engineering to achieve enhancement mode operation. The current blocking layer (CBL) of proposed P-CAVET is hybrid in nature and consist of an oxide part and AlN part. Aluminum Nitride (AlN) portion of CBL is used to lift the triangular well existing at AlGaN/GaN interface above the Fermi level, thus achieving the enhancement mode operation. The CBL provides better suppression of vertical leakage which improves the breakdown voltage. The proposed structure does not need any p-type doping either for achieving enhancement mode operation or for forming current blocking layer. A 2-D calibrated simulation study has revealed that the proposed device exhibits a threshold voltage of 3.1V and breakdown voltage improvement of 100% over the conventional device CAVET.

    关键词： Polarization Engineering,Breakdown Voltage,CAVET,CBL,GaN

    更新于2025-09-23 15:22:29

  • Different Isolation Processes for Free-Standing GaN p-n Power Diode with Ultra-High Current Injection

    摘要： In this article, we report on the fabrication and high performance of power p-n diodes grown on free-standing (FS) GaN substrate. The key technique to enhance the high breakdown voltage and suppress the surface leakage current is the isolation process. The mesa-structure diode is generally formed by utilizing the inductively coupled plasma reactive ion etching (ICP-RIE); however, it always induces high surface damages and thus causes a high leakage current. In this study, we propose a planar structure by employing the oxygen ion implantation to frame the isolation region. By following the crucial process, the fabricated mesa- and planar-type diodes exhibit the turn-on voltages of 3.5 and 3.7 V, specific on-resistance (RONA) of 0.42 and 0.46 mΩ-cm2, and breakdown voltage (VB) of 2640 and 2880 V, respectively. The corresponding Baliga’s figures of merit (BFOM, i.e., VB2/RONA) are 16.6 and 18 GW/cm2, respectively. The BFOM of 18 GW/cm2 is the highest reported value for FS-GaN diode. From the temperature dependent measurements, the planar-type diode also shows the better leakage current and thermal stability than the mesa-type diode.

    关键词： leakage current,Baliga’s figure of merit,breakdown voltage,planar diode,implantation,GaN substrate

    更新于2025-09-23 15:22:29

  • High-voltage regrown nonpolar m-plane vertical p-n diodes: A step toward future selective-area-doped power switches

    摘要： We report high-voltage regrown nonpolar m-plane p-n diodes on freestanding GaN substrates. Secondary-ion mass spectroscopy (SIMS) measurements indicate O and Si spikes at the regrowth interfaces with maximum concentration ~ 5×1017 cm-3, which is similar to previously published c-plane studies. A high blocking voltage of 540 V at ~ 1 mA/cm2 (corresponding to an electric field of E ~ 3.35 MV/cm), turn-on voltages between 2.9-3.1 V, specific on-resistance of 1.7 mΩ.cm2 at 300 A/cm2, and a minimum ideality factor of 1.7 were obtained for the regrown diodes. Our results suggest that Si, O and C interfacial impurity levels up to 2×1017 cm-3, 8×1017 cm-3, and 1×1019 cm-3, respectively, at the metallurgical junction of m-plane p-n diodes do not result in very early breakdown in the reverse bias, although the off-state leakage current in forward bias is affected. The impact of growth interruption/regrowth on diode performance is also investigated.

    关键词： Selective-area doping,GaN,Specific on-resistance,Impurity incorporation,Avalanche breakdown,Leakage currents,Ideality factor,Nonpolar,SIMS,Vertical p-n diodes

    更新于2025-09-23 15:22:29

  • Step-Double-Zone-JTE for SiC Devices with Increased Tolerance to JTE Dose and Surface Charges

    摘要： In this paper, an edge termination structure, referred to as step-double-zone junction termination extension (Step-DZ-JTE), is proposed. Step-DZ-JTE further improves the distribution of the electric field (EF) by its own step shape. Step-DZ-JTE and other termination structures are investigated for comparison using numerical simulations. Step-DZ-JTE greatly reduces the sensitivity of breakdown voltage (BV) and surface charges (SC). For a 30-μm thick epi-layer, the optimized Step-DZ-JTE shows 90% of the theoretical BV with a wide tolerance of 12.2 × 10^12 cm^?2 to the JTE dose and 85% of the theoretical BV with an improved tolerance of 3.7 × 10^12 cm^?2 to the positive SC are obtained. Furthermore, when combined with the field plate technique, the performance of the Step-DZ-JTE is further improved.

    关键词： breakdown voltage (BV),edge termination,junction termination extension (JTE),silicon carbide (SiC)

    更新于2025-09-23 15:22:29

  • Vertical GaN p-n diode with deeply etched mesa and capability of avalanche breakdown

    摘要： A simple structure with high breakdown voltage and low leakage current of a vertical GaN p-n diode on a GaN free-standing substrate is demonstrated. We describe a vertical p-n diode with a simple edge termination that has a drift layer etched deeply and vertically. A device simulation revealed that the electric field was more relaxed at the device edge and applied uniformly in the entire device with increasing etching depth. We fabricated the simulated structure and succeeded in reducing the leakage current and improving the breakdown voltage. With this structure, a stable avalanche breakdown can be observed.

    关键词： avalanche breakdown

    更新于2025-09-23 15:22:29

  • Photothermally Assisted Thinning of Silicon Nitride Membranes for Ultrathin Asymmetric Nanopores

    摘要： Sculpting solid-state materials at the nanoscale is an important step in manufacturing of numerous types of sensor devices, in particular solid-state nanopore sensors. Here we present mechanistic insight into laser-induced thinning of low-stress silicon nitride (SiNx) membranes and films. In a recent study, we observed that focusing a visible wavelength laser beam on a SiNx membrane results in efficient localized heating, and used this effect to control temperature at a solid-state nanopore sensor. A side-effect of the observed heating was that the pores expand/degrade under prolonged high-power illumination, prompting us to study the mechanism of this etching process. We find that SiNx can be etched under exposure to light of ~107 W/cm2 average intensity, with etch rates that are influenced by the supporting electrolyte. Combining this controlled etching with dielectric breakdown, an electrokinetic process for making pores, nanopores of arbitrary dimensions as small as 1-2 nm in diameter and thickness can easily be fabricated. Evidence gathered from biomolecule-pore interactions suggests that the pore geometries obtained using this method are more funnel-like, rather than hourglass-shaped. Refined control over pore dimensions can expand the range of applications of solid-state nanopores, for example, biopolymer sequencing and detection of specific biomarkers.

    关键词： photothermal heating,single-molecule,dielectric breakdown,Nanopores,nanofabrication

    更新于2025-09-23 15:21:21