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Power semiconductor devices are utilized as solid-state switches in power electronics systems, and their overarching design target is to minimize the conduction and switching losses. However, the unipolar figure-of-merit (FOM) commonly used for power device optimization does not directly capture the switching loss. In this Perspective paper, we explore three interdependent open questions for unipolar power devices based on a variety of wide bandgap (WBG) and ultra-wide bandgap (UWBG) materials: (1) What is the appropriate switching FOM for device benchmarking and optimization? (2) What is the optimal drift layer design for the total loss minimization? (3) How does the device power loss compare between WBG and UWBG materials? This paper starts from an overview of switching FOMs proposed in the literature. We then dive into the drift region optimization in 1D vertical devices based on a hard-switching FOM. The punch-through design is found to be optimal for minimizing the hard-switching FOM, with reduced doping concentration and thickness compared to the conventional designs optimized for static FOM. Moreover, we analyze the minimal power loss density for target voltage and frequency, which provides an essential reference for developing device- and package-level thermal management. Overall, this paper underscores the importance of considering switching performance early in power device optimization and emphasizes the inevitable higher density of power loss in WBG and UWBG devices despite their superior performance. Knowledge gaps and research opportunities in the relevant field are also discussed. [ABSTRACT FROM AUTHOR]

Background: The continuation of long-term warfarin therapy is gaining acceptance in minor surgeries but maintaining therapeutic international normalized ratio (INR) values among patients during major orthopedic procedures raises concern. While bridging therapy with low-molecular-weight heparin is currently recommended for patients receiving anticoagulation, few studies have evaluated the safety of continuing warfarin during total joint arthroplasty. This study evaluated the safety and efficacy of continuous warfarin anticoagulation through total joint arthroplasty with and without prophylactic tranexamic acid (TXA). Materials and Methods: We conducted a retrospective, matched-pair analysis of two experimental groups of patients who underwent primary total hip arthroplasty or total knee arthroplasty performed by a single surgeon. Our first experimental group, warfarin plus TXA (warfarin+TXA), consisted of 21 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0–3.0) and who received prophylactic TXA. Our second experimental group, warfarin without TXA (warfarin-TXA), consisted of 40 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0–3.0) without prophylactic TXA. Results: The percent change in hemoglobin value after surgery, red blood cells transfused, surgical site infections, bleeding complications, and thrombotic complications were similar between both experimental and control groups. When comparing the historical group with the warfarin+TXA group, the addition of TXA resulted in a statistical decrease in mean red blood cells transfused and estimated blood loss, with no statistically significant increase in complications. Conclusion: Many factors must be considered when choosing perioperative thromboembolic prophylaxis for arthroplasty candidates with medical comorbidities requiring long-term anticoagulation. This study presents data indicating that it could be safe and effective to continue therapeutic warfarin while using prophylactic TXA. [Orthopedics. 2024;47(4):211–216.] [ABSTRACT FROM AUTHOR]

Power Schottky barrier diodes (SBDs) face an inherent trade-off between forward conduction loss and reverse blocking capability. This limitation becomes more severe for ultra-wide bandgap (UWBG) SBDs due to the large junction field. A high Schottky barrier is usually required to suppress the reverse leakage current at the price of an increased forward voltage drop (VF). This work demonstrates a Ga2O3 junction barrier Schottky (JBS) diode that employs the embedded p-type NiO grids to move the peak electric field away from the Schottky junction, thereby allowing for the use of an ultra-low barrier TiN Schottky contact. This JBS diode concurrently realizes a low VF of 0.91 V (at forward current of 100 A/cm2) and a high breakdown voltage over 1 kV, with the VF being the lowest in all the reported vertical UWBG power diodes. Based on the device characteristics measured up to 200 °C, we further analyze the power loss of this JBS diode across a wide range of operational duty cycles and temperatures, which is found to outperform the TiN/Ga2O3 SBDs or NiO/Ga2O3 PN diodes. These findings underscore the potential of low-barrier UWBG JBS diodes for high-frequency, high-temperature power electronics applications. [ABSTRACT FROM AUTHOR]