Emerging GaN technologies for power, RF, digital, and quantum computing applications: Recent advances and prospects
28 Oct 2021-Journal of Applied Physics (AIP Publishing LLCAIP Publishing)-Vol. 130, Iss: 16, pp 160902
TL;DR: In this article, the authors provide a glimpse of future GaN device technologies and advanced modeling approaches that can push the boundaries of these applications in terms of performance and reliability, which is a key missing piece to realize the full GaN platform with integrated digital, power, and RF electronics technologies.
Abstract: GaN technology is not only gaining traction in power and RF electronics but is also rapidly expanding into other application areas including digital and quantum computing electronics. This paper provides a glimpse of future GaN device technologies and advanced modeling approaches that can push the boundaries of these applications in terms of performance and reliability. While GaN power devices have recently been commercialized in the 15–900 V classes, new GaN devices are greatly desirable to explore both higher-voltage and ultra-low-voltage power applications. Moving into the RF domain, ultra-high frequency GaN devices are being used to implement digitized power amplifier circuits, and further advances using the hardware–software co-design approach can be expected. On the horizon is the GaN CMOS technology, a key missing piece to realize the full-GaN platform with integrated digital, power, and RF electronics technologies. Although currently a challenge, high-performance p-type GaN technology will be crucial to realize high-performance GaN CMOS circuits. Due to its excellent transport characteristics and ability to generate free carriers via polarization doping, GaN is expected to be an important technology for ultra-low temperature and quantum computing electronics. Finally, given the increasing cost of hardware prototyping of new devices and circuits, the use of high-fidelity device models and data-driven modeling approaches for technology-circuit co-design are projected to be the trends of the future. In this regard, physically inspired, mathematically robust, less computationally taxing, and predictive modeling approaches are indispensable. With all these and future efforts, we envision GaN to become the next Si for electronics.
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TL;DR: In this article , the authors review the recent progress of GaN multi-channel power devices and explore the promising perspective of the multichannel platform for future power devices, including multiple, vertically stacked 2DEG channels, showing much reduced resistances and excellent voltage blocking capabilities for a wide range of voltage classes from 1 to 10
Abstract: The outstanding properties of Gallium Nitride (GaN) have enabled considerable improvements in the performance of power devices compared to traditional silicon technology, resulting in more efficient and highly compact power converters. GaN power technology has rapidly developed and is expected to gain a significant market share in an increasing number of applications in the coming years. However, despite the great progress, the performance of current GaN devices is still far from what the GaN material could potentially offer, and a significant reduction of the device on-resistance for a certain blocking voltage is needed. Conventional GaN high-electron-mobility-transistors are based on a single two-dimensional electron gas (2DEG) channel, whose trade-off between electron mobility and carrier density limits the minimum achievable sheet resistance. To overcome such limitations, GaN power devices including multiple, vertically stacked 2DEG channels have recently been proposed, showing much-reduced resistances and excellent voltage blocking capabilities for a wide range of voltage classes from 1 to 10 kV. Such devices resulted in unprecedented high-power figures of merit and exceeded the SiC material limit, unveiling the full potential of lateral GaN power devices. This Letter reviews the recent progress of GaN multi-channel power devices and explores the promising perspective of the multi-channel platform for future power devices.
10 citations
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TL;DR: In this paper , a GaN-on-Si technology based on enhancement-mode p-GaN-gate AlGaN/GaN high electron mobility transistors (HEMTs) and depletion-mode alGaN and GaN HEMTs was proposed and used to implement different digital circuit configurations, namely E/D-mode and E/E-mode (E: enhancement, D: depletion).
Abstract: A study of GaN for high temperature (HT, up to 500 °C) digital circuits was conducted. A HT-robust GaN-on-Si technology based on enhancement-mode p-GaN-gate AlGaN/GaN high electron mobility transistors (HEMTs) and depletion-mode AlGaN/GaN HEMTs was proposed and used to implement different digital circuit configurations, namely E/D-mode and E/E-mode (E: enhancement, D: depletion). The E/D-mode inverter was found to offer significantly better performance in terms of voltage swing, noise margin, and gain, across temperature and ${V}_{\textit {DD}}$ scaling. As calculated from E/D-mode ring oscillators (ROs) with ${L}_{G}=2\,\,\mu \text{m}$ , a RO exhibited a propagation delay ( ${t}_{p}$ ) of < 1.48 ns/stage at 500 °C. The best RO achieved ${t}_{p} < 0.18$ ns/stage at 25 °C. To the best of the authors’ knowledge, the proposed technology sets a new boundary of ${t}_{p}$ vs. ${L}_{G}$ in wide band gap digital logic, and is operational at the highest reported temperature (500 °C) of a GaN digital circuit. The results reflect the promising potential of the proposed technology for emerging HT applications at 500 °C and beyond.
7 citations
01 Mar 2022
TL;DR: In this paper , the authors presented a comprehensive device physics-based study of the GaN Fin-JFET under short-circuit conditions, particularly at a bus voltage close to BV.
Abstract: GaN high-electron-mobility transistors (HEMTs) are known to have no avalanche capability and insufficient short-circuit robustness. Recently, breakthrough avalanche and short-circuit capabilities have been experimentally demonstrated in a vertical GaN fin-channel junction-gate field-effect transistor (Fin-JFET), which shows a good promise for using GaN devices in automotive powertrains and electric grids. In particular, GaN Fin-JFETs demonstrated good short-circuit capability at avalanche breakdown voltage (BV AVA ), with a failure-to-open-circuit (FTO) signature. This work presents a comprehensive device physics-based study of the GaN Fin-JFET under short-circuit conditions, particularly at a bus voltage close to BV AVA . Mixed-mode electrothermal TCAD simulations were performed to understand the carrier dynamics, electric field distributions, and temperature profiles in the Fin-JFET under short-circuit and avalanche conditions. The results provide important physical references to understand the unique robustness of the vertical GaN Fin-JFET under the concurrence of short-circuit and avalanche as well as its desirable FTO signature.
7 citations
TL;DR: The state-of-the-art of the ampere-class Ga2O3 power devices, including their static electrical performance, switching characteristics, packaging and thermal management, and the overcurrent/overvoltage ruggedness and reliability are discussed in this paper .
Abstract: Benefitted from progress on the large-diameter Ga2O3 wafers and Ga2O3 processing techniques, the Ga2O3 power device technology has witnessed fast advances toward power electronics applications. Recently, reports on large-area (ampere-class) Ga2O3 power devices have emerged globally, and the scope of these works have gone well beyond the bare-die device demonstration into the device packaging, circuit testing, and ruggedness evaluation. These results have placed Ga2O3 in a unique position as the only ultra-wide bandgap semiconductor reaching these indispensable milestones for power device development. This paper presents a timely review on the state-of-the-art of the ampere-class Ga2O3 power devices (current up to >100 A and voltage up to >2000 V), including their static electrical performance, switching characteristics, packaging and thermal management, and the overcurrent/overvoltage ruggedness and reliability. Exciting research opportunities and critical technological gaps are also discussed.
7 citations
TL;DR: In this paper , the authors provide a timely review of the thermal management of widebandgap and ultra-wide bandgap power devices with an emphasis on packaged devices, highlighting the pressing needs for device-package electrothermal co-design and high-temperature packages that can withstand the high electric fields expected in UWBG devices.
Abstract: Abstract Power semiconductor devices are fundamental drivers for advances in power electronics, the technology for electric energy conversion. Power devices based on wide-bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors allow for a smaller chip size, lower loss and higher frequency compared with their silicon (Si) counterparts, thus enabling a higher system efficiency and smaller form factor. Amongst the challenges for the development and deployment of WBG and UWBG devices is the efficient dissipation of heat, an unavoidable by-product of the higher power density. To mitigate the performance limitations and reliability issues caused by self-heating, thermal management is required at both device and package levels. Packaging in particular is a crucial milestone for the development of any power device technology; WBG and UWBG devices have both reached this milestone recently. This paper provides a timely review of the thermal management of WBG and UWBG power devices with an emphasis on packaged devices. Additionally, emerging UWBG devices hold good promise for high-temperature applications due to their low intrinsic carrier density and increased dopant ionization at elevated temperatures. The fulfillment of this promise in system applications, in conjunction with overcoming the thermal limitations of some UWBG materials, requires new thermal management and packaging technologies. To this end, we provide perspectives on the relevant challenges, potential solutions and research opportunities, highlighting the pressing needs for device–package electrothermal co-design and high-temperature packages that can withstand the high electric fields expected in UWBG devices.
7 citations
References
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TL;DR: In this paper, an updated version of supplementary information to accompany "Quantum supremacy using a programmable superconducting processor", an article published in the October 24, 2019 issue of Nature, is presented.
Abstract: This is an updated version of supplementary information to accompany "Quantum supremacy using a programmable superconducting processor", an article published in the October 24, 2019 issue of Nature. The main article is freely available at this https URL. Summary of changes since arXiv:1910.11333v1 (submitted 23 Oct 2019): added URL for qFlex source code; added Erratum section; added Figure S41 comparing statistical and total uncertainty for log and linear XEB; new References [1,65]; miscellaneous updates for clarity and style consistency; miscellaneous typographical and formatting corrections.
4,873 citations
TL;DR: In this article, the authors investigated the role of spontaneous and piezoelectric polarization on the carrier confinement at GaN/AlGaN and AlGaN/GaN interfaces.
Abstract: Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face AlxGa1−xN/GaN/AlxGa1−xN and N-face GaN/AlxGa1−xN/GaN heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in heterostructures with AlGaN barrier layers of different Al concentrations (0.15
2,581 citations
Google1, University of Massachusetts Amherst2, Ames Research Center3, California Institute of Technology4, University of California, Santa Barbara5, University of Erlangen-Nuremberg6, Oak Ridge National Laboratory7, University of California, Riverside8, Forschungszentrum Jülich9, RWTH Aachen University10, University of Michigan11, University of Illinois at Urbana–Champaign12
TL;DR: Quantum supremacy is demonstrated using a programmable superconducting processor known as Sycamore, taking approximately 200 seconds to sample one instance of a quantum circuit a million times, which would take a state-of-the-art supercomputer around ten thousand years to compute.
Abstract: The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor1. A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits2-7 to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 253 (about 1016). Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times-our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy8-14 for this specific computational task, heralding a much-anticipated computing paradigm.
2,527 citations
TL;DR: A redshift that is strongly dependent on pump power supports the idea that the electron–hole plasma mechanism is primarily responsible for the gain at room temperature and is a considerable advance towards the realization of electron-injected, nanowire-based ultraviolet–blue coherent light sources.
Abstract: There is much current interest in the optical properties of semiconductor nanowires, because the cylindrical geometry and strong two-dimensional confinement of electrons, holes and photons make them particularly attractive as potential building blocks for nanoscale electronics and optoelectronic devices, including lasersand nonlinear optical frequency converters. Gallium nitride (GaN) is a wide-bandgap semiconductor of much practical interest, because it is widely used in electrically pumped ultraviolet-blue light-emitting diodes, lasers and photodetectors. Recent progress in microfabrication techniques has allowed stimulated emission to be observed from a variety of GaN microstructures and films. Here we report the observation of ultraviolet-blue laser action in single monocrystalline GaN nanowires, using both near-field and far-field optical microscopy to characterize the waveguide mode structure and spectral properties of the radiation at room temperature. The optical microscope images reveal radiation patterns that correlate with axial Fabry-Perot modes (Q approximately 10(3)) observed in the laser spectrum, which result from the cylindrical cavity geometry of the monocrystalline nanowires. A redshift that is strongly dependent on pump power (45 meV microJ x cm(-2)) supports the idea that the electron-hole plasma mechanism is primarily responsible for the gain at room temperature. This study is a considerable advance towards the realization of electron-injected, nanowire-based ultraviolet-blue coherent light sources.
1,207 citations
TL;DR: Several device technologies for realizing normally off operation that is highly desirable for power switching applications are presented and the examples of circuit applications that can greatly benefit from the superior performance of GaN power devices are demonstrated.
Abstract: In this paper, we present a comprehensive reviewand discussion of the state-of-the-art device technology and application development of GaN-on-Si power electronics. Several device technologies for realizing normally off operation that is highly desirable for power switching applications are presented. In addition, the examples of circuit applications that can greatly benefit from the superior performance of GaN power devices are demonstrated. Comparisonwith other competingpower device technology, such as Si superjunction-MOSFET and SiC MOSFET, is also presented and analyzed. Critical issues for commercialization of GaN-on-Si power devices are discussed with regard to cost, reliability, and ease of use.
922 citations