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Evaluation of Switching Loss Contributed by Parasitic Ringing for Fast Switching Wide Band-Gap Devices
摘要： Parasitic ringing is commonly observed during the high-speed switching of wide band-gap (WBG) devices. Additional loss contributed by parasitic ringing becomes a concern especially for high switching frequency applications. This paper investigates the effects of parasitic ringing on switching loss of WBG devices in a phase-leg configuration. An analytical switching loss model considering parasitics in power devices and application circuit is derived. Two switching commutation modes, gate drive dominated mode and power loop dominated mode, are investigated, respectively, and the switching loss induced by damping ringing is identified. It is found that this portion of the loss is at most the energy stored in parasitics, which always exists regardless of the switching speed and parasitic ringing. Therefore, with the given WBG device in the specific application circuit, damping more severe parasitic ringing during faster switching transient would not introduce higher switching loss. Additionally, the extra switching loss induced by resonance among parasitics and cross-talk is investigated. It is observed that severe resonance and its resultant over-voltage during the turn-on transient worsens the cross-talk, causing large shoot-through current and excessive switching loss. The theoretical analysis has been verified by the double pulse test with a 1200-V/50-A SiC-based phase-leg power module.
关键词： fast speed switching,switching loss,parasitic ringing,overshoot voltage,cross-talk,Wide Bandgap
更新于2025-09-09 09:28:46
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RF Performance of Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with 80 nm Gates
摘要： Al-rich AlGaN-channel high electron mobility transistors (HEMTs) with 80 nm long gates and 85% (70%) Al in the barrier (channel) were evaluated for RF performance. DC characteristics include a maximum current of 160 mA/mm with transconductance of 24 mS/mm, limited by source and drain contacts, and an on/off current ratio of 109. fT of 28.4 GHz and fMAX of 18.5 GHz were determined from small-signal S-parameter measurements. Output power density of 0.38 W/mm was realized at 3 GHz in a power sweep using on-wafer load pull techniques.
关键词： high electron mobility transistor,Ultra-wide-bandgap,RF performance,HEMT,aluminum gallium nitride
更新于2025-09-09 09:28:46
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Influence of heavy alkali post deposition treatment on wide gap Cu(In,Ga)Se2
摘要： The effect of Potassium, Rubidium, and Cesium post deposition treatment (PDT) on wide bandgap Cu(In,Ga)Se2 (CIGSe) absorbers has been investigated. The results show that the efficiency of the cells can be improved by the alkali treatment and a higher value of the open-circuit-voltage (VOC) can be achieved. In spite of this improvement, the activation energy (EA) of the treated samples remained smaller than the bandgap (Eg) and VOC(t) transients under red light showed a negative slope. Hence, the wide gap CIGSe devices remain limited by recombination at the interface. However, the VOC(t)-transient of treated and untreated samples with the same Eg show a different slope (d Δ?????? (??)/dt). CIGSe samples treated with heavy alkalis (RbF- and CsF-PDT) illustrate a smaller slope in comparison to no-PDT and KF-PDT samples. In this contribution, we discuss the Voc(t) slope, i.e. d Δ?????? (??)/dt, with reference to the illumination dependent doping density (NA,a) and to a possible Sodium exchange mechanisms.
关键词： alkali treatment,wide bandgap,Ga)Se2,Cu(In,recombination,post deposition treatment,solar cells,open-circuit-voltage
更新于2025-09-09 09:28:46
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High Temperature Operation Limit Assessment for 4H-SiC Schottky Diode-based Extreme Temperature Sensors
摘要： We developed a simplified theoretical model for parameters calculation of diode temperature sensors (DTS) based on Schottky diodes (SD). The current flow mechanism of the diodes considered was dominated by over-barrier thermionic emission. Qualitative correlations between basic fundamental and electrophysical parameters of such DTS were established. The expressions for ultimate high-temperature parameters of the DTS were obtained. Theoretical results obtained were approved using test samples of DTS with Schottky contact Ni/n-SiC (4H). It was shown that physical high-temperature limit of operation of such a DTS (>1250 K) exceeded the values of commercial DTS based on Si, GaAs, AlGaAs p-n junctions. And the SD-based DTS itself demonstrated significantly lower energy consumption.
关键词： wide bandgap,thermal sensitivity,high temperature,Schottky diode,temperature sensor,semiconductor,thermal limit
更新于2025-09-09 09:28:46
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Gallium Oxide || Properties of sputter-deposited gallium oxide
摘要： The wide bandgap oxides, such as ZrO2, Y2O3, HfO2, La2O3, Ga2O3, and GeO2, have been the focus of much attention in recent years due to their wide range of applications in optical, electronic and optoelectronic, photonic, and magnetoelectronic devices [1–12]. Gallium oxide (Ga2O3), one among these wide bandgap oxides, has been receiving recent attention of scientific and research community for its fascinating physical, chemical, and electronic properties, which can be readily utilized in numerous technological applications. Often quoted by several research groups, despite the great promise, properties and potential applications of these wide bandgap materials such as Ga2O3 have not yet fully explored.
关键词： optical properties,wide bandgap oxides,mechanical properties,Gallium oxide,sputter-deposited
更新于2025-09-09 09:28:46
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Gallium Oxide || Low-field and high-field transport in β-Ga2O3
摘要： β-Ga2O3 has recently emerged as a novel wide-bandgap semiconductor with immense potential for applications in power electronics and optoelectronics. Experimental advancements in the past 5 years have been significant toward realizing commercial β-Ga2O3 devices in the near future [1–7]. Matured crystal growth and processing techniques make the material further promising [8–10]. In terms of power electronic applications, MOSFETs based on this material have been demonstrated that could withstand record high voltages [11, 12]. The accuracy of n-type doping and the difficulty of p-type doping make electrons the primary charge carriers in β-Ga2O3. Although β-Ga2O3 has lower electron mobility compared to other wide-bandgap semiconductors, it is found to have a superior Baliga’s figure of merit that jointly accounts for on-state resistance and breakdown voltage [4]. So it is important to investigate in rigor the fundamentals behind β-Ga2O3 material properties that could be beneficial to gain an understanding on the causes that control mobility and breakdown voltage. There are theoretical reports on fundamental materials aspects including electronic structure [13] and optical properties [14], lattice dynamical and dielectric properties [15], and thermal properties [16, 17] as well. The primary physics behind both mobility (and hence the device on resistance) and breakdown voltage lies in the electron transport phenomenon. There have been a few experimental reports that try to characterize the electron transport and scattering mechanisms in β-Ga2O3 with Hall measurements being reported a few times to predict temperature dependence and also crystal orientation dependence of the electron mobility [18, 19]. On the other hand, we are making a systemic study on the theoretical understanding of electron transport in β-Ga2O3 starting from the first principles [20–22]. The main idea is to follow a bottom-up approach in order to develop an understanding of the near-equilibrium and far-from-equilibrium electron dynamics in β-Ga2O3. This is unique compared to conventional semiconductors in a way that β-Ga2O3 has a low-symmetry crystal structure and a fairly large primitive unit cell that gives rise to many phonon modes. On several occasions, the traditional notions of electron transport that are applicable to Si and GaAs actually do not quite hold well in the case of β-Ga2O3. In this chapter, we attempt to provide a comprehensive picture of electron transport in β-Ga2O3 under low and moderately high electric fields based on our work in the recent years.
关键词： electron-phonon interaction,β-Ga2O3,electron mobility,power electronics,optoelectronics,electron transport,velocity-field curves,wide-bandgap semiconductor
更新于2025-09-09 09:28:46
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Gallium Oxide || Radiation damage in Ga2O3
摘要： β-Ga2O3 has a large bandgap of approximately 4.9 eV and an estimated critical electric field (EC) strength of 8 MV/cm. The large bandgap of β-Ga2O3 allows high-temperature device operation and this large critical field allows high-voltage operation (relative to maximum breakdown) and the most common device structure reported to date has been Schottky rectifiers. This material also has potential in devices with low power loss during high-frequency switching in the GHz regime. Similarly, Ga2O3-based photodetectors are attracting interest for their promise as truly solar-blind deep ultraviolet (UV) photodetectors exhibiting cut-off wavelengths below 280 nm. These would have applications in detection of UV wavelengths for military applications, air purification, space communication, ozone-layer monitoring, and flame sensing.
关键词： β-Ga2O3,photodetectors,radiation damage,Schottky rectifiers,wide bandgap semiconductors
更新于2025-09-09 09:28:46
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Gallium Oxide || Ga2O3 nanobelt devices
摘要： β-Gallium oxide (β-Ga2O3) is attractive as a novel material for (opto)electronics, especially high-power electronics and solar-blind photodetectors (PDs). It has an ultrawide direct bandgap of around 4.8–4.9 eV at room temperature and high thermal and chemical stabilities [1, 2]. The theoretical electrical breakdown field (Ebr) of β-Ga2O3 is known to be (cid:1)8 MV/cm, and 3.8 MV/cm of Ebr has been experimentally demonstrated in a recent report, recording a higher value than those of GaN and SiC. Baliga’s figure of merit (BFOM) of β-Ga2O3 is also superior among some of the other popular wide-bandgap semiconductors, such as 4H-SiC and GaN [3–6]. These outstanding properties have led to a large number of reports on various electrical devices based on β-Ga2O3 including metal-oxide-semiconductor field-effect transistors (MOSFETs), metal-semiconductor field-effect transistors (MESFETs), and Schottky barrier diodes [7–10]. Furthermore, the wide bandgap of β-Ga2O3 provides intrinsic solar blindness that allows fabrication of solar-blind PDs without the need for additional optical filters that block light in the range of long wavelength [11]. Single-crystal β-Ga2O3 is commercially available as a various of growth methods exist; especially the edge-defined film-fed growth (EFG) method that can be used to grow bulk β-Ga2O3 substrates with high crystal quality [12, 13]. However, the low thermal conductivity of β-Ga2O3 has to be considered when fabricating high-power electrical devices.
关键词： high-power electronics,β-Ga2O3,wide-bandgap semiconductors,optoelectronics,solar-blind photodetectors
更新于2025-09-09 09:28:46
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Gallium Oxide || Power MOSFETs and diodes
摘要： Gallium oxide-based transistors and diodes possess fundamental electronic properties that make it an ideal candidate for high-power devices. A number of these properties derive directly from the wide bandgap of Ga2O3 (Eg ? 4.85 eV) including an exceptionally high electric breakdown field (approximately 8 MV/cm). This high breakdown field allows Ga2O3-based devices to be biased at a high drain voltage (Vbreak-down ? 100 V) while maintaining a large dynamic range. Furthermore, the wide bandgap of Ga2O3 allows device operation at elevated temperature (>300°C) without degradation. In addition, Ga2O3 has a high saturation electron velocity (vsat ? 2 (cid:2) 107 cm/s), which is partially accountable for the high current density, Imax (Imax (cid:3) qnvsat, where q ? 1.6 (cid:2) 10(cid:4)19 coulomb, n ? charge density, and vs ? electron saturation velocity). Despite the relatively low thermal conductivity of Ga2O3, the rapid development of high-quality native Ga2O3 substrates lowers the overall cost of production and avoids many of the defect-related issues that have hampered GaN and SiC devices. It is expected that Ga2O3-based devices will be competitive with Si-based medium-power as well as GaN and SiC-based high-power electronic devices.
关键词： Gallium oxide,high electric breakdown field,high saturation electron velocity,high-power devices,wide bandgap
更新于2025-09-09 09:28:46
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Epitaxial growth of undoped and Li-doped NiO thin films on α–Al2O3 substrates by mist chemical vapor deposition
摘要： Undoped and Li-doped NiO thin films were grown on α-Al2O3 (0001) substrates by mist chemical vapor deposition. Both undoped and Li-doped NiO thin films grew bi-epitaxially on the substrates with crystallographic orientation relationships of NiO(111)[ˉ110]?||?α-Al2O3(0001)[01ˉ10] and NiO(111)[1ˉ10]?||?α-Al2O3(0001)[01ˉ10]. In the Li-doped NiO thin film, a periodic structure was observed, in accordance with a mirror-symmetrical oxygen layer on the terraces of the substrate. Both undoped and Li-doped NiO thin films exhibited high transmittance (>80%) in the visible-light region and optical bandgaps of 3.7–3.8 eV. The undoped NiO thin film showed insulating properties and a resistivity of 106 ??cm or higher. In contrast, the Li-doped NiO thin films had resistivities of 101–105 ??cm, depending on the Li precursor concentration. Furthermore, they exhibited positive Seebeck coefficients, indicating their p-type conductivity. These results indicate that Li dopants effectively act as acceptors in NiO thin films.
关键词： A3.Mist CVD,B1.Nickel oxide,B2.Wide bandgap oxide semiconductor,B1.Li-doped nickel oxide
更新于2025-09-09 09:28:46