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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Review of Ultrafast Switching Power Modules: Trends, Challenges, and Technical Solutions

Benefiting from the superior properties of wide-bandgap semiconductor materials, wide-bandgap power devices demonstrate exceptional switching performance, enabling more efficient and compact power electronics systems. However, ultrafast switching poses challenges to the reliability of the system in terms of severe oscillations and voltage overshoot, electromagnetic interference, and increased risk of partial discharge. By developing advanced power module packaging for fast-switching power devices, the above-mentioned challenges can be mitigated at the packaging level, enabling the full utilization of the fast-switching capability of wide-bandgap devices. Meanwhile, such technology also lays the groundwork for packaging next-generation power devices with even higher blocking voltage and faster switching speed. In this paper, a comprehensive review of ultrafast switching power modules has been made, including the benefits and status of ultrafast switching power modules, challenges brought by ultrafast switching, and promising technologies to address these challenges. In addition, future development trends and research gaps are also discussed in this paper. Furthermore, this review can serve as a reference for future wide-bandgap power module packaging design.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Adroit Materials Final Scientific/Technical Report kV-class GaN-based Junction Barrier Schottky diodes using ion implantation

The primary aim of this research was to develop GaN-based Junction Barrier Schottky (JBS) diodes using an innovative ion implantation process previously established in ARPA-E funded projects. The central focus of our proposed technology revolves around selective area p-type doping, accomplished through the implantation of Mg ions. This approach builds upon our successes in the ARPA-E PNDIODES program, advancing towards commercial device integration. Selective area p-doping plays a pivotal role in realizing the next generation of GaN-based power devices, capable of significantly reducing the carbon footprint in the United States by several million tons. While ion implantation is a well-established technique for achieving selective area doping in SiC and Si materials, its feasibility in GaN had not been demonstrated until now. To fabricate high voltage GaN JBS diodes, we initially created thick n-type drift layers with high carrier concentrations ranging from 5×1015 cm-3 to 2×1016 cm-3 and very high mobilities. Subsequently, Mg ions were selectively implanted to form p-type islands within the n-type drift layer. To reduce electric field crowding at the edge of the diode and to achieve high breakdown voltage, junction edge termination (JTE) and floating field rings (FFRs) were formed using Mg implantation. A high temperature, high-pressure post-implantation annealing process was carried out to activate the implanted Mg ions. As a result, we were able to demonstrate GaN JBS diodes with a breakdown voltage of 915 V and an on-resistance of 0.6 mΩ·cm2. These diodes exhibited a forward bias current density of 1 kA/cm2 at 1.5 V. Subsequently, we achieved GaN JBS diodes with a remarkable breakdown voltage of 1900 V and an on-resistance of 1.9 mΩ·cm2, capable of sustaining a forward bias current density of 0.5 kA/cm2 at 1.5 V. Importantly, the ON and OFF state performance of these GaN JBS diodes surpassed that of Si and SiC-based power diodes reported in existing literature. Lastly, we successfully grew 60 μm thick GaN:Si layers using HVPE with a carrier concentration of approximately 3 to 5×1015 cm-3. Based on simulation and empirical data these devices represent 5 kV GaN JBS power diodes, leveraging the developed processes in this project.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Rugged WBG Devices and Advanced Electric Machines for High Power Density Automotive Electric Vehicles

This work explored two very important approaches for supporting transportation electrification and reducing dependence on imports of critical materials. In the first task, several novel electric machine architectures with low rare earth metal content were compared analytically, then experimentally to verify their performance. Rare earth metals are imported largely from China and are widely used in many clean energy systems such as wind turbines and EV motors. Reducing our dependence on this critical material is an important objective for ensuring our independence and continued economic prosperity. In the second task, a GaN based inverter for EV inverters was developed to demonstrate the suitability of that wide bandgap semiconductor device in this important application.

42 ENGINEERING↗
DOE OSTI2022

Assessment of dislocation reduction on 100 mm diameter bulk GaN grown by the NEAT method

X-ray topography measurements on a 100 mm diameter GaN boule grown by the Near Equilibrium AmmonoThermal method revealed an improvement in dislocation density from >1 × 10 6 cm -2 to between 2 × 10 5 and 5 × 10 5 cm -2, an improvement greater than two to five times from seed to growth. This data builds on previous X-ray diffraction and defect selective etching to quantify the reduction in defect density that is closely associated with increasing growth thickness. This result indicates that there is a pathway to further dislocation reduction by increasing growth thickness for GaN crystals including those of 100 mm or larger diameter. Further reduction of the dislocation density of large-area substrates will lead to GaN power devices with reduced leakage current under reverse bias and better device performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Thermal and Mechanical Design of a High-Voltage Power Electronics Package: Preprint

Thermal and mechanical design aspects of a power electronic package with 5-kV GaN devices are presented. Through finite element analyses, the impact of different cooling configurations and device location on the thermal performance and reliability of the package was investigated. It was found that placing the devices closer to the direct-bond-copper substrate as opposed to a centered approach in the proposed double-sided-cooling configuration resulted in improved heat dissipation. This approach also reduced the total number of attachment layers, thereby likely improving the reliability of the package. Furthermore, simulations revealed that the device location had a negligible impact on the thermomechanical behavior of the attachment layers, as they are more prone to the local coefficient of thermal expansion mismatch.

27 ARPA - Advanced Research Projects Agency-Energy↗
DOE OSTI2022

Phase I Final Report

Explore the source record for details and available documents.

photocathode, gallium nitride, GaN↗
DOE OSTI2022

Precise electron beam-based target-wavelength trimming for frequency conversion in integrated photonic resonators

We demonstrate post-fabrication target-wavelength trimming with a gallium phosphide on a silicon nitride integrated photonic platform using controlled electron-beam exposure of hydrogen silsesquioxane cladding. A linear relationship between the electron-beam exposure dose and resonant wavelength red-shift enables deterministic, individual trimming of multiple devices on the same chip to within 30 pm of a single target wavelength. Second harmonic generation from telecom to near infrared at a target wavelength is shown in multiple devices with quality factors on the order of 10 4 . Post-fabrication tuning is an essential tool for targeted wavelength applications including quantum frequency conversion.

Thiel, Lillian↗
DOE OSTI2024

Creation of color centers in diamond by recoil implantation through dielectric films

The need of near-surface color centers in diamond for quantum technologies motivates the controlled doping of specific extrinsic impurities into the crystal lattice. Further, recent experiments have shown that this can be achieved by momentum transfer from a surface precursor via ion implantation, an approach known as “recoil implantation.” Here, we extend this technique to incorporate dielectric precursors for creating nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers in diamond. Specifically, we demonstrate that gallium focused-ion-beam exposure to a thin layer of silicon nitride or silicon dioxide on the diamond surface results in the introduction of both extrinsic impurities and carbon vacancies. These defects subsequently give rise to near-surface NV and SiV centers with desirable properties after annealing.

42 ENGINEERING↗
DOE OSTI2020

High-efficiency solar thermophotovoltaic system using a nanostructure-based selective emitter

Herein, we present the design, fabrication, optimization, and experimental results of a high-efficiency planar solar thermophotovoltaic (STPV) system utilizing a micro-textured absorber and a nanostructure multilayer metal-dielectric coated selective emitter fabricated on a tungsten (W) substrate. Light absorptance of more than 90% was achieved at visible and near-infrared wavelengths using the microtextured absorbing surface. The nanostructure selective emitter consists of two thin-film optical coatings of silicon nitride (Si3N4) and a layer of W in between to increase the surface emissivity in spectral regimes matching the quantum efficiency of the thermophotovoltaic (TPV) cells. Gallium antimonide (GaSb)-based TPV cells are used in our STPV design. The experiment was conducted at different operating temperatures using a high-power continuous wave laser diode stack as a simulated source of concentrated incident radiation. Our experimental setup measured a maximum electrical output power density of 1.71 W/cm 2 at 1676 K STPV temperature, and the overall power conversion efficiency of 8.4% after normalizing the output power density to the emitter area. This is the highest STPV system efficiency reported so far for any experimental STPV device. The incident optical laser power on the absorber side was 131 W. This is equivalent to a solar concentration factor of ~2100, which is within the practical limit and readily achievable with Fresnel lens setup.

14 SOLAR ENERGY↗
DOE OSTI2020

Beryllium Oxide (BeO) Handbook

Beryllium oxide (BeO) is an oxide ceramic material. BeO ceramics provide thermal conductivity second only to diamond among electrically insulating materials, dissipating nearly 300 W/mK at room temperature. This property leads to electronic applications for BeO. BeO has a thermal expansion coefficient intermediate between gallium arsenide and refractory metal composites. Its low dielectric constant (6.7) and low loss index (0.0012 at 1 MHz) permits electrical circuit performance at high frequencies. It is employed as a window material for high frequency microwave applications. BeO is very stable under oxidizing and reducing high temperature and high humidity environments, unlike nitrides which will decompose to their oxide equivalent. Similar to beryllium metal, BeO acts as a scatterer of neutrons and is used as a neutron moderator material in nuclear reactor applications. The largest use of BeO is as the raw material for the manufacture of beryllium-copper alloys, followed closely as the raw material for conversion to beryllium metal. Most of the research performed on BeO was conducted in the 1960’s and 1970’s. 75% of the references cited in this Handbook are from the time period 1960-1980. Up to 1995, there were three commercial sources of BeO: Materion Corporation, Eagle-Picher, and Ceradyne Corporation. However, since 1995 Eagle-Picher and Ceradyne no longer supply BeO commercial products. Thus, the only current commercial source of BeO materials is Materion Corporation.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Neutral but Impactful: Gallium Cluster-Induced Nanopores from Beam-Blanked Gallium Ion Sources

Neutral atoms originating from liquid metal ion sources are an often-overlooked source of contamination and damage in focused ion beam microscopy. Beyond ions and single atoms, these sources also generate atom clusters. While most studies have investigated charged clusters, here we demonstrate that neutral clusters are also formed. These neutral clusters bypass the electrostatic beam blanking system, allowing them to impinge on samples even when the ion beam is blanked. We investigate this phenomenon using thin (≤20 nm) freestanding membranes of hexagonal boron nitride, silicon, and silicon nitride as targets. Randomly dispersed nanopores that form upon neutral cluster exposure are revealed. The average nanopore diameter is ∼2 nm with a narrow size distribution, suggesting that the atom clusters have a preferred size. Various electron microscopy techniques are used to characterize the nanopores, including high-resolution transmission electron microscopy, multislice ptychography, and electron energy-loss spectroscopy. Finally, we show how electron irradiation in the transmission electron microscope can be used to both remove any amorphous material that may clog the pores and to controllably grow the pores to specific sizes. Tunable nanopores such as these are interesting for nanofluidic applications requiring size-selective membranes.

Byrne, Dana O↗
DOE OSTI2024

An Organic, Direct Bonded Copper, Multi-Layered, Ultra-Low Inductance Package for High-Power UWBG MOSFETs

The most common metalized substrates used in high-power switching packages consist of a ceramic layer such as Aluminum Nitride (AlN) sandwiched between two copper layers. Ceramic substrates are used because it has the key characteristic of having high dielectric strength while being thermally conductive. A large drawback to ceramic substrates is that they do not allow for a multi-layered circuit design. By replacing the traditional ceramic substrate with organic direct bonded copper (ODBC) we can open a wide range of possibilities when it comes to power module layout such as multi-layered circuits and double-sided cooling. Both benefits are critical while packaging high-performance Gallium Oxide (Ga2O3) MOSFETs. Because of Ga2O3's relatively poor thermal conductivity, a double-sided cooled package becomes necessary. Therefore, the use of ODBC provides the flexibility to fabricate copper traces carrying much higher currents, and by creating a multi-layered package, we can drastically reduce the parasitic inductance inside the power module. Achieving lower parasitic inductance is critical for an ultra-fast Ga2O3 package to avoid excessive voltage overshoot and ringing. Using ODBC, we have designed novel packages capable of handling the challenges presented by fast Ga2O3 switching. Using multi-physics modeling software, we can validate our design before building the prototype. Due to the simple process parameters needed to work with ODBC, we can rapidly create prototypes without using external vendors. This flexibility allows us to quickly design, build, and validate highly complex switching power modules to accommodate next generation, Ga2O3 switching devices.

ADVANCED PROPULSION SYSTEMS,ENGINEERING↗
DOE OSTI2022

Amorphous 2D Materials – A Novel Platform for Remote Epitaxy and Nanopatterned Epitaxy of III-V Semiconductors with Low Decomposition Temperatures

III-V semiconductor materials such as indium phosphide (InP) offer outstanding photonic properties that outperforms silicon, but the cost of these wafers is extremely expensive. Although reusing original wafers can effectively minimize the cost, current techniques for wafer recycling of these substrates add significant costs in fabrication, nullifying the cost savings by reusing the wafers. Besides, unlike other III-V materials such as gallium arsenide (GaAs), commonly used epitaxial lift-off method for wafer recycling is not well studied for materials like InP due to lack of lattice-matched sacrificial layers, which makes reusing these wafers more difficult. Remote epitaxy and nanopatterned epitaxy are newly discovered methods that enable single-crystal growth of III-V semiconductor thin films and easy exfoliation of these grown films, thus promising for a new cost-effective pathway of reusing wafers. However, previous methods of transferring two-dimensional (2D) materials, which use polymethyl methacrylate (PMMA) or metal stressor layers to transfer 2D materials grown on foreign substrates like copper (Cu) or silicon carbide (SiC), introduce defects and damages on the 2D layer and/or substrates during the transfer process. Remote epitaxial and nanopatterned epitaxial films grown on the damaged 2D layer/substrate suffer from lower crystal quality and imperfect exfoliation, which undermines wafer reusability and device performance. Here we report the MBE growth of amorphous boron nitride (a-BN) on InP wafers at low temperature that enabled improved quality of remote epitaxial and nanopatterned epitaxial films and their perfect exfoliation. We show fully covered a-BN on InP substrates despite their low decomposition temperatures. The surface of a-BN coated InP substrate remains smooth with a RMS roughness of around 3Â. We also demonstrate 100% coverage of single-crystal InP thin films grown on a-BN, with the film's quality significantly improved compared to the case of transferred 2D materials. In addition, the growth and exfoliation were successfully repeated multiple times, proving the feasibility for InP wafer recycling. Through this low temperature MBE growth approach with remote epitaxy and nanopatterned epitaxy, we successfully demonstrate large-scale flexible thin film exfoliation and recycling of InP substrates, which will lead to new opportunities in InP thin film-based photonics and novel heterostructures with significantly reduced cost.

Lu, Kuangye↗