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Showing papers on "Gallium nitride published in 2021"


BookDOI
08 Oct 2021
TL;DR: A survey of research on Gallium Nitride can be found in this paper, where the authors discuss the role of Hydrogen in GaN and Related Compounds in the development of GaN.
Abstract: 1. Plate Type Exchangers 2. Dynamic Systems 3. A Historical Survey of Research on Gallium Nitride 4. Growth of Group III Nitrides from Molecular Beams 5. Ternary Alloys 6. Optical Characterization of GaN and Related Materials 7. Theoretical Studies in GaN 8. GaAsN Alloys and GaN/GaAs Thin Layer Structures 9. The Contribution of Defects to the Electrical and Optical Properties of GaN 10. Growth of GaN Single Crystals Under High Nitrogen Pressure 11.Ion Implantation Doping and Isolation of III-Nitride Materials 12. High-Density ECR Etching of Group-III Nitrides 13. Contacts on III-Nitrides 14. III-V Nitride Based LEDs 15. III-V Nitride Electronic Devices 16. Physical Properties of the Bulk GaN Crystals Grown by the High-Pressure, High Temperature Method 17. Microstructure of Epitaxial III-V Nitride Thin Films 18. The Role of Hydrogen in GaN and Related Compounds

194 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe the physics, technology, and reliability of GaN-based power devices, starting from a discussion of the main properties of the material, the characteristics of lateral and vertical GaN transistors are discussed in detail to provide guidance in this complex and interesting field.
Abstract: Over the last decade, gallium nitride (GaN) has emerged as an excellent material for the fabrication of power devices. Among the semiconductors for which power devices are already available in the market, GaN has the widest energy gap, the largest critical field, and the highest saturation velocity, thus representing an excellent material for the fabrication of high-speed/high-voltage components. The presence of spontaneous and piezoelectric polarization allows us to create a two-dimensional electron gas, with high mobility and large channel density, in the absence of any doping, thanks to the use of AlGaN/GaN heterostructures. This contributes to minimize resistive losses; at the same time, for GaN transistors, switching losses are very low, thanks to the small parasitic capacitances and switching charges. Device scaling and monolithic integration enable a high-frequency operation, with consequent advantages in terms of miniaturization. For high power/high-voltage operation, vertical device architectures are being proposed and investigated, and three-dimensional structures—fin-shaped, trench-structured, nanowire-based—are demonstrating great potential. Contrary to Si, GaN is a relatively young material: trapping and degradation processes must be understood and described in detail, with the aim of optimizing device stability and reliability. This Tutorial describes the physics, technology, and reliability of GaN-based power devices: in the first part of the article, starting from a discussion of the main properties of the material, the characteristics of lateral and vertical GaN transistors are discussed in detail to provide guidance in this complex and interesting field. The second part of the paper focuses on trapping and reliability aspects: the physical origin of traps in GaN and the main degradation mechanisms are discussed in detail. The wide set of referenced papers and the insight into the most relevant aspects gives the reader a comprehensive overview on the present and next-generation GaN electronics.

141 citations


Journal ArticleDOI
01 Aug 2021
TL;DR: In this article, the authors report the monolithic integration of enhancementmode n-channel and p-channel GaN field-effect transistors and the fabrication of GaN-based complementary logic integrated circuits.
Abstract: Owing to its energy efficiency, silicon complementary metal–oxide–semiconductor (CMOS) technology is the current driving force of the integrated circuit industry. Silicon’s narrow bandgap has led to the advancement of wide-bandgap semiconductor materials, such as gallium nitride (GaN), being favoured in power electronics, radiofrequency power amplifiers and harsh environment applications. However, the development of GaN CMOS logic circuits has proved challenging because of the lack of a suitable strategy for integrating n-channel and p-channel field-effect transistors on a single substrate. Here we report the monolithic integration of enhancement-mode n-channel and p-channel GaN field-effect transistors and the fabrication of GaN-based complementary logic integrated circuits. We construct a family of elementary logic gates—including NOT, NAND, NOR and transmission gates—and show that the inverters exhibit rail-to-rail operation, suppressed static power dissipation, high thermal stability and large noise margins. We also demonstrate latch cells and ring oscillators comprising cascading logic inverters. Through the monolithic integration of enhancement-mode n-type and p-type gallium nitride field-effect transistors, complementary integrated circuits including latch circuits and ring oscillators can be created for use in high-power and high-frequency applications.

97 citations



Journal ArticleDOI
TL;DR: In this article, the authors present details of photoluminescence (PL) spectroscopy experiments and discuss possible sources of mistakes, as well as a brief analysis of near-band-edge emission.
Abstract: Photoluminescence (PL) spectroscopy is a powerful tool in studying semiconductor properties and identifying point defects. Gallium nitride (GaN) is a remarkable semiconductor material for its use in a new generation of bright white LEDs, blue lasers, and high-power electronics. In this Tutorial, we present details of PL experiments and discuss possible sources of mistakes. A brief analysis of near-band-edge emission includes basic characterization of GaN, essential findings about excitons in this material, and the explanation of less known details. We review modern approaches of quantitative analysis of PL from point defects in GaN. The updated classification of defects in undoped GaN and their latest identifications are presented. Typical mistakes in the interpretation of PL spectra from GaN are discussed, and myths about PL are refuted.

56 citations


Journal ArticleDOI
TL;DR: In this article, the bonding configurations of a-Si:H are investigated, in order to manipulate the extinction coefficient and produce a material that is competitive with conventional transparent materials, such as titanium dioxide and gallium nitride.
Abstract: The high refractive index of hydrogenated amorphous silicon (a-Si:H) at optical frequencies is an essential property for the efficient modulation of the phase and amplitude of light. However, substantial optical loss represented by its high extinction coefficient prevents it from being utilized widely. Here, the bonding configurations of a-Si:H are investigated, in order to manipulate the extinction coefficient and produce a material that is competitive with conventional transparent materials, such as titanium dioxide and gallium nitride. This is achieved by controlling the hydrogenation and silicon disorder by adjusting the chemical deposition conditions. The extinction coefficient of the low-loss a-Si:H reaches a minimum of 0.082 at the wavelength of 450 nm, which is lower than that of crystalline silicon (0.13). Beam-steering metasurfaces are demonstrated to validate the low-loss optical properties, reaching measured efficiencies of 42%, 62%, and 75% at the wavelengths of 450, 532, and 635 nm, respectively. Considering its compatibility with mature complementary metal-oxide-semiconductor processes, the low-loss a-Si:H will provide a platform for efficient photonic operating in the full visible regime.

55 citations


Journal ArticleDOI
02 May 2021
TL;DR: In this paper, a heterostructure of two-dimensional molybdenum disul... is proposed for high-performance broadband photodetectors with narrow spectral sensitivity.
Abstract: Narrow spectral sensitivity in materials is one of the crucial challenges to develop high-performance broadband photodetectors. Here, we design a heterostructure of two-dimensional molybdenum disul...

51 citations


Journal ArticleDOI
TL;DR: By deploying a surface reinforcement layer (SRL) at the interface between Schottky metal and GaN in the gate stack, a gate high-electron-mobility transistor (HEMT) with enhanced gate reliability is demonstrated in this paper.
Abstract: By deploying a surface reinforcement layer (SRL) at the interface between Schottky metal and ${p}$ -GaN in the gate stack, a ${p}$ -GaN gate high-electron-mobility transistor (HEMT) with enhanced gate reliability is demonstrated. Prior to the gate metal deposition, the SRL is formed by an oxygen-plasma treatment and a subsequent high-temperature annealing process (at 800 °C) that enables surface reconstruction. Such a process converts several nanometers of ${p}$ -GaN near the surface into a crystalline GaON layer, which exhibits stronger immunity to hot electron bombardment. With nearly identical threshold voltage and ON -resistance, the ${p}$ -GaN gate HEMT with SRL yields two orders of magnitude reduction in gate leakage current at ON -state and an increase from 10.5 V to 12.7 V in forward gate breakdown voltage. Time-dependent gate breakdown measurement reveals an increase from 5.9 V to 7.8 V in the maximum ON -state gate drive voltage for a 10-year lifetime with a 1 % gate failure rate, which effectively expands the operating voltage margin of the ${p}$ -GaN gate power HEMT.

50 citations


Journal ArticleDOI
TL;DR: In this article, the performance of four commercial gallium-nitride (GaN) power devices in a wide temperature range between 400 and 4.2 K was investigated and compared, showing the promising potential of the GaN technology for low-temperature applications and providing precious insights to properly design power systems operating under cryogenic temperatures and maximize their efficiency.
Abstract: Gallium nitride (GaN) power devices are employed in an increasing number of applications thanks to their excellent performance. Nevertheless, their potential for cryogenic applications, such as space, aviation, and superconducting systems, has not yet been fully explored. In particular, little is known on the device performance below liquid nitrogen temperature (77 K) and the behavior of popular GaN architectures such as gate injection transistor and Cascode below room temperature has not yet been reported. Most importantly, it is still unclear how the different device loss contributions, i.e., conduction, soft- and hard-switching losses, change at cryogenic temperatures. In this letter, we investigate and compare the performance of four GaN commercial power devices in a wide temperature range between 400 and 4.2 K. All of the tested devices can successfully operate at cryogenic temperatures with an overall performance improvement. However, different GaN HEMT technologies lead to significant variations in device gate control and loss mechanisms, which are discussed based on the device structure. The presented results prove the promising potential of the GaN technology for low-temperature applications and provide precious insights to properly design power systems operating under cryogenic temperatures and maximize their efficiency.

47 citations


Journal ArticleDOI
TL;DR: In this article, the avalanche and surge current ruggedness of the industry's first 1.2kV-class vertical GaN p-n diodes fabricated on 100mm GaN substrates was reported.
Abstract: This letter reports the avalanche and surge current ruggedness of the industry's first 1.2-kV-class vertical GaN p-n diodes fabricated on 100-mm GaN substrates. The 1.2-kV vertical GaN p-n diodes with a 1.39-mm2 device area and an avalanche breakdown voltage of 1589 V show a critical avalanche energy density of 7.6 J/cm2 in unclamped inductive switching tests, as well as a critical surge current of 54 A and a critical surge energy density of 180 J/cm2 in 10-ms surge current tests. All these values are the highest reported in vertical GaN devices and comparable to those of commercial SiC p-n diodes and merged p-n Schottky diodes. These GaN p-n diodes show significantly smaller reverse recovery compared to SiC p-n diodes, revealing less conductivity modulation in n-GaN. The negative temperature coefficient of differential on-resistance and the anticlockwise surge I–V locus are believed to be due to the increased acceptor ionization in p-GaN and the decreased contact resistance at high temperatures. These results suggest a high ruggedness of GaN p-n junctions with small bipolar currents and fast switching capabilities. As the first electrothermal ruggedness data for industry's vertical GaN devices, these results provide key new insights for the development of vertical GaN devices as well as their application spaces.

47 citations


Journal ArticleDOI
TL;DR: In this paper, the authors highlight the importance of nanoscale thermal transport mechanisms at each layer in material hierarchies that make up modern electronic devices, including those mechanisms that impact thermal transport through: substrates, interfaces and two-dimensional materials, and heat spreading materials.
Abstract: This review introduces relevant nanoscale thermal transport processes that impact thermal abatement in power electronics applications. Specifically, we highlight the importance of nanoscale thermal transport mechanisms at each layer in material hierarchies that make up modern electronic devices. This includes those mechanisms that impact thermal transport through: (1) substrates, (2) interfaces and two-dimensional materials, and (3) heat spreading materials. For each material layer, we provide examples of recent works that (1) demonstrate improvements in thermal performance and/or (2) improve our understanding of the relevance of nanoscale thermal transport across material junctions. We end our discussion by highlighting several additional applications that have benefited from a consideration of nanoscale thermal transport phenomena, including radio frequency (RF) electronics and neuromorphic computing. [DOI: 10.1115/1.4049293]

Journal ArticleDOI
22 Apr 2021
TL;DR: In this paper, the authors presented the application of wide bandgap (WBG) semiconductor devices with cryogenic cooling and demonstrated the feasibility of operating high-power SiC converter with Cryogenic cooling.
Abstract: This article presents the cryogenically cooled application for wide bandgap (WBG) semiconductor devices. Characteristics of silicon carbide (SiC) and gallium nitride (GaN) at cryogenic temperatures are illustrated. SiC MOSFETs exhibit increased on-state resistance and slower switching speed at cryogenic temperatures. However, cryogenic cooling provides low ambient temperature environment and thus enables the SiC converter to operate at lower junction temperature to achieve higher efficiency compared to room temperature cooling. A cryogenically cooled MW-level SiC inverter prototype is developed and demonstrated the feasibility of operating high-power SiC converter with cryogenic cooling. GaN HEMTs exhibit more than five times on-state resistance reduction and faster switching speed at cryogenic temperatures which makes GaN HEMTs an excellent candidate for cryogenic power electronics applications. The significantly reduced on-state resistance of GaN devices provides the possibility to operate them at a current level much higher than rated current at cryogenic temperatures. A GaN double pulse test (DPT) circuit is constructed and demonstrated that GaN HEMTs can operate at nearly four times of rated current at cryogenic temperatures. Challenges of utilizing WBG device with cryogenic cooling are discussed and summarized.

Journal ArticleDOI
TL;DR: In this article, the authors present a pedagogical presentation of the models of electronic states, their effects on device performance, and the presently accepted approaches to minimize their effects such as surface passivation and insulated gate technologies.
Abstract: Gallium nitride (GaN) is one of the front-runner materials among the so-called wide bandgap semiconductors that can provide devices having high breakdown voltages and are capable of performing efficiently even at high temperatures. The wide bandgap, however, naturally leads to a high density of surface states on bare GaN-based devices or interface states along insulator/semiconductor interfaces distributed over a wide energy range. These electronic states can lead to instabilities and other problems when not appropriately managed. In this Tutorial, we intend to provide a pedagogical presentation of the models of electronic states, their effects on device performance, and the presently accepted approaches to minimize their effects such as surface passivation and insulated gate technologies. We also re-evaluate standard characterization methods and discuss their possible pitfalls and current limitations in probing electronic states located deep within the bandgap. We then introduce our own photo-assisted capacitance–voltage (C–V) technique, which is capable of identifying and examining near mid-gap interface states. Finally, we attempt to propose some directions to which some audience can venture for future development.

Journal ArticleDOI
TL;DR: In this article, the photoelectrochemically self-improving behavior of a silicon/gallium nitride photocathode for hydrogen production with a Faradaic efficiency approaching 100% was investigated.
Abstract: Development of an efficient yet durable photoelectrode is of paramount importance for deployment of solar-fuel production. Here, we report the photoelectrochemically self-improving behaviour of a silicon/gallium nitride photocathode active for hydrogen production with a Faradaic efficiency approaching ~100%. By using a correlative approach based on different spectroscopic and microscopic techniques, as well as density functional theory calculations, we provide a mechanistic understanding of the chemical transformation that is the origin of the self-improving behaviour. A thin layer of gallium oxynitride forms on the side walls of the gallium nitride grains, via a partial oxygen substitution at nitrogen sites, and displays a higher density of catalytic sites for the hydrogen-evolving reaction. This work demonstrates that the chemical transformation of gallium nitride into gallium oxynitride leads to sustained operation and enhanced catalytic activity, thus showing promise for oxynitride layers as protective catalytic coatings for hydrogen evolution. Development of efficient yet durable photoelectrodes is of paramount importance for deployment of solar-fuel production. The photoelectrochemically self-improving behaviour of a silicon/gallium nitride photocathode highly efficient for hydrogen production is now reported.

Journal ArticleDOI
TL;DR: In this paper, a new atomic layer deposition (ALD) ruthenium (Ru) gate metallization process was used to control the DC-RF dispersion and increase the conductivity in the access regions.
Abstract: This letter reports on the $W$ -band power performance of N-polar GaN deep recess MIS–high electron mobility transistors (HEMTs) using a new atomic layer deposition (ALD) ruthenium (Ru) gate metallization process. The deep recess structure is utilized to control the DC-RF dispersion and increase the conductivity in the access regions. The ALD Ru effectively fills the narrow T-gate stems aiding realization of shorter gate lengths with lower gate resistance than in prior work. In this work, the gate length was scaled down to 48 nm, resulting in the demonstration of a record high 8.1-dB linear transducer gain measured at 94 GHz by load pull. This increased gain has enabled a record 33.8% power-added efficiency (PAE) with an associated output power density ( $P_{\mathrm {O}}$ ) of 6.2 W/mm.

Journal ArticleDOI
TL;DR: In this article, the authors proposed the shift to the aluminum nitride (AlN) platform, which allows for smarter, highly-scaled heterostructure design that will improve the output power and thermal management of III-nitride amplifiers.
Abstract: Gallium nitride high-electron-mobility transistors (GaN HEMTs) are at a point of rapid growth in defense (radar, SATCOM) and commercial (5G and beyond) industries. This growth also comes at a point at which the standard GaN heterostructures remain unoptimized for maximum performance. For this reason, we propose the shift to the aluminum nitride (AlN) platform. AlN allows for smarter, highly-scaled heterostructure design that will improve the output power and thermal management of III-nitride amplifiers. Beyond improvements over the incumbent amplifier technology, AlN will allow for a level of integration previously unachievable with GaN electronics. State-of-the-art high-current p-channel FETs, mature filter technology, and advanced waveguides, all monolithically integrated with an AlN/GaN/AlN HEMT, is made possible with AlN. It is on this new AlN platform that nitride electronics may maximize their full high-power, high-speed potential for mm-wave communication and high-power logic applications.

Journal ArticleDOI
TL;DR: In this article, a quasi-vertical GaN junction barrier Schottky diode on a low-cost sapphire substrate was reported, achieving a reverse leakage in level of 10−7 A/cm2, as well as a high on/off current ratio of 1010 and a high breakdown voltage of 838 V.
Abstract: In this letter, we report a quasi-vertical GaN junction barrier Schottky diode on low-cost sapphire substrate. With the high quality GaN epitaxy and selective-area p-islands formed via Magnesium ion implantation at the anode region, reverse leakage in level of 10−7 A/cm2 was achieved, as well as a high on/off current ratio of 1010 and a high breakdown voltage of 838 V. Meanwhile, advantageous characteristics as expected in vertical GaN Schottky barrier diode were realized, including a low turn-on voltage of 0.5 V and fast switching performance under 400 V/10 A operation condition. Along with the improved heat dissipation via substrate thinning and packaging techniques, the diode retains a relatively low thermal resistance, enabling high current rectification level over 60 A, power efficiency up to 98.7 %, while maintaining low case temperatures.

Journal ArticleDOI
TL;DR: In this article, a solar-blind ultraviolet detector was fabricated based on β-Ga2O3/GaN nanowires heterojunction, which has the advantages of easy preparation, low dark current, high rejection ratio, fast response, good stability and repeatability.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate scaled-up GaN-on-Si tri-Anode Schottky barrier diodes (SBDs), whose excellent dc and switching performance are compared to commercial Si fast-recovery dioders and SiC SBDs.
Abstract: Gallium nitride (GaN) transistors are being employed in an increasing number of applications thanks to their excellent performance and competitive price. Yet, GaN diodes are not commercially available, and little is known about their performance and potential impact on power circuit design. In this article, we demonstrate scaled-up GaN-on-Si Tri-Anode Schottky barrier diodes (SBDs), whose excellent dc and switching performance are compared to commercial Si fast-recovery diodes and SiC SBDs. Moreover, the advantageous lateral GaN-on-Si architecture enables the integration of several devices on the same chip, paving the way for power integrated circuits (ICs). This is demonstrated by realizing a diode-multiplier IC, which includes up to eight monolithically integrated SBDs on the same chip. The IC was integrated on a dc–dc magnetic-less boost converter able to operate at a frequency of 1 MHz. The IC performance and footprint are compared to the same circuit realized with discrete Si and SiC vertical devices, showing the potential of GaN power ICs for efficient and compact power converters.

Journal ArticleDOI
TL;DR: In this paper, a comprehensive review summarizes the current progress, understanding, and challenges in vertical GaN power devices, which can serve as not only a gateway for those interested in the field but also a critical reference for researchers in the wide bandgap semiconductor and power electronics community.
Abstract: Vertical gallium nitride (GaN) power devices are enabling next-generation power electronic devices and systems with higher energy efficiency, higher power density, faster switching, and smaller form factor. In Part I of this review, we have reviewed the basic design principles and physics of building blocks of vertical GaN power devices, i.e., Schottky barrier diodes and p-n diodes. Key topics such as materials engineering, device engineering, avalanche breakdown, and leakage mechanisms are discussed. In Part II of this review, several more advanced power rectifiers are discussed, including junction barrier Schottky (JBS) rectifiers, merged p-n/Schottky (MPS) rectifiers, and trench metal–insulator–semiconductor barrier Schottky (TMBS) rectifiers. Normally- OFF GaN power transistors have been realized in various advanced device structures, including current aperture vertical electron transistors (CAVETs), junction field-effect transistors (JFETs), metal–oxide–semiconductor field-effect transistors (MOSFETs), and fin field-effect transistors (FinFETs). A detailed analysis on their performance metrics is provided, with special emphasis on the impacts of key fabrication processes such as etching, ion implantation, and surface treatment. Lastly, exciting progress has been made on selective area doping and regrowth, a critical process for the fabrication of vertical GaN power devices. Various materials characterization techniques and surface treatments have proven to be beneficial in aiding this rapid development. This timely and comprehensive review summarizes the current progress, understanding, and challenges in vertical GaN power devices, which can serve as not only a gateway for those interested in the field but also a critical reference for researchers in the wide bandgap semiconductor and power electronics community.

Journal ArticleDOI
TL;DR: In this article, the authors presented the design and experimental characterization of a $K$ -band high power amplifier (HPA) monolithic microwave-integrated circuit (MMIC) for the next generation of very high throughput satellites (vHTS).
Abstract: This letter presents the design and experimental characterization of a $K$ -band high power amplifier (HPA) monolithic microwave-integrated circuit (MMIC) for the next generation of very high throughput satellites (vHTS). The MMIC is a three-stage balanced amplifier realized on a commercial 100-nm gate length gallium nitride on silicon (GaN-Si) technology. The design is compliant with space reliability constraints and, despite the larger thermal resistance and losses shown by the silicon (Si) substrate with respect to the more common silicon carbide (SiC), the realized HPA delivers, in pulsed condition, a peak output power larger than 41 dBm in the operative band from 17.3 to 20.2 GHz, with an associated power added efficiency (PAE) and gain up to 40% and 26 dB, respectively. In continuous wave (CW) operative conditions and with a backside temperature of 85 °C, the MMIC delivers a minimum output power and PAE of 39.4 dBm and 28%, respectively. Moreover, a 24-h test at saturated power has shown almost negligible performance degradations, thus providing confidence in the selected GaN-Si technology’s robustness.

Journal ArticleDOI
TL;DR: In this article, a SPICE-compatible equivalent circuit model is presented according to the structure of Schottky-type p-GaN gate HEMTs, which features a floating node to imitate the charge storage process within the gate stack.
Abstract: The threshold voltage ( V TH) of an enhancement-mode Schottky-type p -GaN gate high-electron-mobility transistor (HEMT) is found to have a special dependence on the drain bias. The device commonly requires higher gate voltage to switch on the transistor from a high-drain-voltage off -state than what is expected from the static device characteristics. The reason behind the dynamic V TH has been proved to be the floating p -GaN layer, where charges could be stored and further influence V TH under different drain bias. In this article, a SPICE-compatible equivalent circuit model is presented according to the structure of Schottky-type p -GaN gate HEMTs. It features a floating node to imitate the charge storage process within the gate stack. Compared to conventional models, the proposed model could accurately predict the dynamic V TH characteristics and switching behaviors of power electronics circuits, where Schottky-type p -GaN gate HEMTs are deployed as power transistors. The phenomena related to the dynamic V TH, including the disappearance of Miller plateau, the overestimated false-turn- on problem, and the higher reverse conduction loss are evaluated with a half-bridge circuit and the merits of the proposed model are verified.

Journal ArticleDOI
TL;DR: In this article, the authors explored the large-signal RF performance of high-electron-mobility transistors on the AlN/GaN/AlN heterostructure.
Abstract: The AlN/GaN/AlN heterostructure is attractive for microwave and millimeter-wave power devices due to its thin top barrier, tight carrier confinement, and improved breakdown voltage. This work explores the large-signal RF performance of high-electron-mobility transistors on this heterostructure. Results are highlighted by record high on-current of 3.6 A/mm, and record maximum oscillation frequency ( $f_{max}$ ) of 233 GHz. The load-pull power sweep at 10 GHz demonstrate a peak power added efficiency (PAE) of 22.7% with an associated gain ( $G_{T}$ ) of 8.7 dB and output power ( $P_{out}$ ) of 3 W/mm. When optimized for power, the peak $P_{out}$ of 3.3 W/mm has an associated PAE of 14.7% and $G_{T}$ of 3.2 dB. This first demonstration is encouraging for the mm-wave power potential of the AlN/GaN/AlN HEMT.

Journal ArticleDOI
TL;DR: In this article, the Tamm-Fano resonance in gold/porous semiconductor photonic crystal has been used as an alternative multilayer Bragg reflector for biosensing measurements.
Abstract: Biophotonic sensing techniques are an accurate best way for biosensing measurements. The main aim of the proposed device is to make a more effective sensor to detect the change in the refractive index of a sample. This sensor is based on the Tamm–Fano resonance in gold/porous semiconductor photonic crystal. Porous Gallium nitride has been used as an alternative multilayer Bragg reflector. The proposed structure composed of prism/Au/porous GaN/(GaN/porous GaN) N/substrate. The numerical studies for the proposed structure are calculated using the transfer matrix method. The sensitivity, FoM, and Q-factor observed from this device are 3 × 104 nm/RIU, 6.6 × 104 RIU−1, and 9 × 108. This study records sensitivity 2875 times higher than the experimental study of a similar structure in other wavelength range. The proposed sensor can be used in biosensing applications because it records high local environment sensitivity.

Journal ArticleDOI
TL;DR: In this paper, the authors show that the RON increase and decrease during stress and recovery experiments in carbon-doped AlGaN/GaN power metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs).
Abstract: RON degradation due to stress in GaN-based power devices is a critical issue that limits, among other effects, long-term stable operation. Here, by means of 2-D device simulations, we show that the RON increase and decrease during stress and recovery experiments in carbon-doped AlGaN/GaN power metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) can be explained with a model based on the emission, redistribution, and retrapping of holes within the carbon-doped buffer (“hole redistribution” in short). By comparing simulation results with front- and back-gating OFF-state stress experiments, we provide an explanation for the puzzling observation of both stress and recovery transients being thermally activated with the same activation energy of about 0.9 eV. This finds a straightforward justification in a model in which both RON degradation and recovery processes are limited by hole emission by dominant carbon-related acceptors that are energetically located at about 0.9 eV from the GaN valence band.

Journal ArticleDOI
TL;DR: In this article, a graphite-embedded insulated metal substrate (thermally-annealed-pyrolytic-graphite embeddings) was proposed for widebandgap power modules.
Abstract: Emerging wide-bandgap (WBG) semiconductor devices such as silicon carbide (SiC) metal–oxide semiconductor field-effect transistors (MOSFETs) and gallium nitride high-electron-mobility transistors can handle high power in reduced semiconductor areas better than conventional Si-based devices owing to superior material properties. With increased power loss density in a WBG-based converter and reduced die size in power modules, thermal management of power devices must be optimized for high performance. This article presents a graphite-embedded insulated metal substrate (thermally-annealed-pyrolytic-graphite-embedded insulated metal substrate—IMSwTPG) designed for WBG power modules. Theoretical thermal performance analysis of graphite-embedded metal cores is presented, with design details for IMSwTPG with embedded graphite to replace a direct-bonded copper (DBC) substrate. The proposed IMSwTPG is compared with an aluminum nitride-based DBC substrate using finite-element thermal analysis for steady-state and transient thermal performance. The solutions’ thermal performances are compared under different coolant temperature and thermal loading conditions, and the proposed substrate's electrical performance is validated with static and dynamic characterization. Using graphite-embedded substrates, junction-to-case thermal resistance of SiC MOSFETs can be reduced up to 17%, and device current density can be increased by 10%, regardless of the thermal management strategy used to cool the substrate. Reduced transient thermal impedance of up to 40% of dies owing to increased heat capacity is validated in transient thermal simulations and experiments. The half-bridge power module's electrical performance is evaluated for on -state resistance, switching performance, and switching loss at three junction temperature conditions. The proposed substrate solution has minimal impact on conduction and switching performance of SiC MOSFETs.

Journal ArticleDOI
01 Jun 2021
TL;DR: In this article, BAs and BP cooling substrates can be heterogeneously integrated with metals, a widebandgap semiconductor (gallium nitride, GaN) and high-electron-mobility transistor devices.
Abstract: Thermal management is critical in modern electronic systems. Efforts to improve heat dissipation have led to the exploration of novel semiconductor materials with high thermal conductivity, including boron arsenide (BAs) and boron phosphide (BP). However, the integration of such materials into devices and the measurement of their interface energy transport remain unexplored. Here, we show that BAs and BP cooling substrates can be heterogeneously integrated with metals, a wide-bandgap semiconductor (gallium nitride, GaN) and high-electron-mobility transistor devices. GaN-on-BAs structures exhibit a high thermal boundary conductance of 250 MW m−2 K−1, and comparison of device-level hot-spot temperatures with length-dependent scaling (from 100 μm to 100 nm) shows that the power cooling performance of BAs exceeds that of reported diamond devices. Furthermore, operating AlGaN/GaN high-electron-mobility transistors with BAs cooling substrates exhibit substantially lower hot-spot temperatures than diamond and silicon carbide at the same transistor power density, illustrating their potential for use in the thermal management of radiofrequency electronics. We attribute the high thermal management performance of BAs and BP to their unique phonon band structures and interface matching. Boron arsenide and boron phosphide cooling substrates can be integrated with other materials, including the wide-bandgap semiconductor gallium nitride, creating structures that exhibit high thermal boundary conductances and high-electron-mobility transistors that exhibit low hot-spot temperatures.

Proceedings ArticleDOI
13 Feb 2021
TL;DR: In this article, a GaN-on-Si structure is shown in Fig. 33.1, and there are severe heterogeneous defects between the GaN buffer layer and the Si substrate.
Abstract: Gallium-Nitride (GaN) high-electron-mobility transistors (HEMTs) have the advantages of low parasitic capacitance, low on-resistance $(R_{ON})$, and no reverse recovery charge loss [1–5]. Thus, using GaN HEMTs one can optimize the performance of power integrated circuits. However, today’s GaN HEMTs have serious process defects, especially depending on the selected substrate. A 650V GaN-on-Si structure is shown in Fig. 33.1.1, and there are severe heterogeneous defects between the GaN buffer layer and the Si substrate. Thus, temperature changes will seriously aggravate the hot carrier injection, and the two-dimensional electron gas (2DEG) layer in the GaN HEMT will weaken over time. The on-resistance $(R_{ON})$ and threshold voltage $(V_{TH,E})$ of 650 GaN HEMT gradually increase, and in turn, rapidly decline the reliability. Although state-of the-art gate drivers can effectively reduce the ringing at the V GS of the GaN switch [4–6], the temperature reliability problem still exists. The tri-slope gate control in [4] adjusts the sourcing current I Control to drive the gate voltage V G . The active slew-rate control method in [6] uses different gate resistors R G1 and R G2 to control the driving current I G . Both control techniques did not consider temperature-dependent threshold voltage. To completely reduce parasitic effects, monolithic integration of gate driver and GaN HEMT in GaN-on-Si process has been shown in [3, 7]. However, they did not carefully consider the reliability degradation caused by the variations of $V_{TH,E}$ and Miller plateau voltage due to temperature effects. High switching operations enlarge the temperature effect on monolithic integration.

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TL;DR: In this paper, anode materials of silicon carbide and III-nitride nanosheets are investigated for magnesium ion batteries (MIBs) as possible alternative of lithium and sodium ion batteries.

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TL;DR: In this paper, the authors provide a review on the significant research work done in the field of GaN based sensor technologies, classified the work done so far, according to the applications and the different types of parameters being measured.
Abstract: Gallium Nitride (GaN) belongs to III-N family of compound semiconductors, which albeit new, is well-established material system in the fields of high power, high temperature electronics and optoelectronics. Also, its properties such as high mobility, surface sensitivity, non-toxicity, thermal endurance, low power consumption make it an ideal material for realizing sensors. This paper provides a review on the significant research work done in the field of GaN based sensor technologies. We classified the work done so far, according to the applications and the different types of parameters being measured. The challenges faced by the current sensing systems and future opportunities are also briefly explained for a variety of applications viz. radiation sensors, mechanical sensors, gas sensors, biosensors, chemical sensors and high temperature Hall-effect sensors etc. Additionally, the sensing mechanism of various sensors is explained. This paper can supply initial reading material for beginners and research students working on GaN heterostructure based sensor applications.