Gallium Nitride Field Effect Transistors Research Articles

Dielectrically-Modulated GANFET Biosensor for Label-Free Detection of DNA and Avian Influenza Virus: Proposal and Modeling

This paper introduces a novel device called the Gate All Around Engineered Gallium Nitride Field Effect Transistor (GAAE-GANFET), designed specifically for label-free biosensing applications. This innovative gate-all-around engineering in GANFET integrates various device engineering techniques, such as channel engineering, gate engineering, and oxide engineering, to enhance biosensing performance. The channel engineering techniques refer to the use of a gallium nitride channel with a step-graded doping profile, divided into three distinct regions. In contrast, the gate engineering technique refers to the cylindrical split-gate-underlap architecture. The oxide engineering technique involves stacking Al2O3 and HfO2. Moreover, this biosensor incorporates two-sided gate underlap cavities that facilitate the immobilization of biomolecules. These open cavities not only provide structural stability but also simplify the fabrication process to a significant extent. The viability of this biosensor as a label-free biosensor has been evaluated using an antigen and an antibody from the Avian Influenza virus and DNA as the target biomolecules. The proposed analytical model and TCAD simulation results are in excellent agreement, demonstrating the reliability of the proposed device. Additionally, the biosensor’s sensitivity, which depends on cavity length, doping concentration, gate metal work function, and temperature variation, has been thoroughly explored. The gate-all-around structure, along with the integration of tri-step graded doping, GaN as the channel material, gate oxide stacking, and dual open cavity structure in the proposed biosensor, leads to significantly improved biosensing capabilities.

Design and Implementation of GaN-Based Two Switch Flyback With Synchronous Rectification for New Space Applications

This article presents a comprehensive investigation and implementation of a continuous conduction mode pulse width modulated two-switch DC/DC flyback converter utilizing Gallium Nitride Field Effect Transistors (GaNFETs) for New Space applications. The New Space concept advocates for the integration of Commercial Off-The-Shelf (COTS) materials in the space industry. The approach offers cost-effective solutions and reduces lead time for space designs. The study provides steady-state analysis and design considerations for two switch flyback converters, highlighting the transformative capabilities of GaNFETs, especially in high-frequency operations. The rationale behind the preference for GaNFETs over MOSFETs in satellite power supply applications and the strategic benefits of COTS materials are explained in detail. In addition, the synchronous rectification method is implemented to obtain better efficiency, particularly for high-output current operations. The converter achieves an efficiency of over 87% when the load exceeds 50%, with varying input voltages from 20 V to 40 V and a switching frequency of 300 kHz. The experimental findings show that the designed converter can serve as a high efficiency and reliable satellite power converter.

Analysis of high‐frequency electromagnetic ringing phenomenon under GaN‐FET inverter excitation

AbstractIn this study, the ringing phenomenon of gallium nitride‐field effect transistor (GaN‐FET) and silicon‐insulated gate bipolar transistor (Si‐IGBT) inverter excitations in a ring sample was thoroughly measured and analyzed by using a high‐quality oscilloscope with a very high sampling rate of 5 giga‐samples per second (GS/s). Owing to the rapid switching of the GaN‐FET power devices in several nanoseconds and the ringing frequencies in the MHz range, the use of the high sampling rate of 5 GS/s is necessary and useful for accurate measurement. The experimental findings and analysis reveal the following three key points: (i) there are two possible types of high‐frequency resonance phenomena, that is, the first one caused by semiconductor devices and circuits and the other generated by the resonance with loads in use. (ii) The ringing phenomenon because of the resonance under the load is considered to be due to the rising time of pulses that are caused by the rapid switching of the semiconductor devices. (iii) The ability to measure and the two types of ringing phenomena depends on the intensity of the white noise of the measuring instrument

Reduction in the Number of Current Sensors of a Semi-Bridgeless PFC Rectifier Based on GaNFET Characteristics

The semi-bridgeless power factor correction (PFC) rectifier is widely used due to its high power factor, high efficiency, and low electromagnetic interference. However, in this rectifier, the inductor current will flow through the body diode of the metal–oxide–semiconductor field-effect transistor (MOSFET) when the MOSFET does not work, causing a problem in detecting the inductor current. Consequently, the current transformers are generally used as current sensors. This means that using many current sensors will make the cost and the peripheral detection circuit complicated. In this paper, our new method is to use a gallium nitride field-effect transistor (GaNFET) to replace the metal–oxide–semiconductor field-effect transistor (MOSFET) in the main switch selection. The reverse-biased conduction voltage of the third quadrant of the GaNFET is higher than the forward-biased conduction voltage of the diode, which solves the problem in detecting the inductor current, reduces the number of current sensors, and simplifies the corresponding peripheral circuits and components. Eventually, via mathematical deduction and hardware implementation, a semi-bridgeless PFC prototype with a GaNFET was built to verify the effectiveness of the proposed structure.

Picosecond and high-power UV/Vis light pulsing using gallium nitride field-effect transistors: implementation and design evaluation

This paper discusses the development of cost-effective and high-performance picosecond and high-power light pulsers. The use of innovative gallium nitride field-effect transistor technology, in combination with meticulous electronic design and careful selection of light-emitting diodes or laser diodes for ultraviolet and visible spectral ranges, has resulted in superior characteristics compared to commonly used designs. The sub-ns design achieves pulse widths as low as 300 ps, with photon outputs ranging between 104-109 photons per pulse, over a wavelength range of 235-470 nm. Meanwhile, the high-power design achieves pulse widths as low as 1.8 ns, with photon outputs ranging between 107-1011 photons per pulse, and a wavelength range of 375-525 nm. The two designs complement each other in photon outputs, covering a dynamic range of almost ten orders of magnitude. This paper provides an evaluation of the electrical design and emitter selection of both pulsers, as well as their electrical and optical performance.

Simplified Gate Driver Design Technique for Multi-MHz Switching GaN FETs in Three-Level Buck-Based 4G/5G Envelope Tracking

Multi-MHz switching frequency converter-based envelope tracking dc power supplies are widely adopted in modern 4G/5G communication base stations to improve the efficiency of radio frequency power transmitters. The switching loss of buck converter at MHz switching frequency increases with the input dc voltage. To obtain higher output voltage range without much compromise on the efficiency, multilevel converters with discrete low voltage gallium nitride (GaN) field-effect transistors (FETs), switching at multi-MHz frequency, are used. However, the gate driving circuit and PCB layout of a multilevel buck converter are complex and occupy major portion of the board when compared with the power GaN FETs. This article proposes a simplified gate driving technique in a cascaded bootstrapping architecture for a three-level buck converter with reduced number of components that can support up to 40 MHz switching frequency. The converter can reproduce any reference envelope signal with a maximum bandwidth of 8 MHz and output voltage variation from 6 to 42 V. Hardware prototype is developed, and experimental results are presented to validate the concept.

Unveiling the parasitic electron channel under the gate of enhancement-mode p-channel GaN field-effect transistors on the p-GaN/AlGaN/GaN platform

Enhancement-mode (E-mode) p-channel gallium nitride (GaN) field-effect transistors (p-FETs) are essential components for GaN-based complementary logic circuits. For the ease of integration with n-FETs, they could be fabricated on the commercial p-GaN gate high-electron-mobility-transistor (HEMT) platform, on which the two-dimensional electron gas at the AlGaN/GaN hetero-interface is completely depleted in as-grown epi-structures. However, under the gated region where p-GaN is recessed and depleted at thermal equilibrium, a parasitic electron channel (PEC) could appear at the AlGaN/GaN interface. This Letter reports experimental investigations on the PEC with specifically designed structures, confirming that the PEC does exist but imposes limited impacts on electrical characteristics of p-FETs. When connected with an external contact, the PEC could act as a back gate to modulate the overlaying p-channel. If isolated from external contacts, which is the case of p-FETs under normal operations, electrons in the PEC would redistribute under the active region of p-FETs in the horizontal direction (i.e., parallel to the surface) under different biases but are mostly confined near the AlGaN/GaN interface in the vertical direction (i.e., perpendicular to the surface).

Time- and Frequency-Domain Characterization of Switching Losses in GaN FETs Power Converters

This article presents a methodology for the time-frequency characterization of switching losses in Gallium nitride field effect transistors used in power electronics applications, particularly in dc–dc converters. Typically, switching losses are measured in the time-domain through the integration of the instantaneous power, that is, the product of the voltage multiplied by the current, during the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> transients. Nonetheless, as novel power transistors allow for switching times in the nanosecond range, the accuracy of such measurements is compromised by the limitations of the probe-oscilloscope systems in terms of bandwidth and dynamic range. Here, we analyze the time-domain switching loss measurement method, and then, through a complementary setup we demonstrate how to validate the results in the frequency domain. A dc–dc half-bridge buck converter circuit based on the EPC2001C was used as a representative test sample. Less than 1% of difference in critical parameters such as rise-time, pulse width, state-levels and, switching frequency, is encountered between the time- and frequency-domain approaches. Moreover, the measurement uncertainty was analyzed and estimated to be between ±1% and ±8%. This article allows for highly confident switching loss measurements, a better understanding of the switching phenomena and of the measurement system performance.

Dead Time Optimization in a GaN-Based Buck Converter

A gallium nitride (GaN) field effect transistor can provide superior performance over a Si- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> due to its low <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state resistance and low junction capacitances. However, a GaN-based converter exhibits higher dead time loss during reverse conduction. Thus, to improve the efficiency, dead time optimization is required. This article proposes simple models for dead time optimization in a GaN-based buck converter under different load conditions. The proposed models are analytical in nature compared to the conventional models available for Si-based converters. A buck converter prototype is designed using a 100 V GaN device (GS61008P from GaN Systems) and the proposed analytical model-based dead time optimization techniques are validated experimentally. The proposed modeling techniques can be extended for other GaN-based dc–dc converters.

Enhancing Lifetime of 1U/2U CubeSat Electric Power System With Distributed Architecture and Power-Down Mode

The successful mission of CubeSat require reliable and fault-tolerant electrical power system (EPS) that powers all the other subsystems and payloads. Several studies have shown that EPS failure has been one of the main contributors for the CubeSat mission failure. The main objective of this paper is to enhance the lifetime of CubeSats EPS by proposing a distributed EPS architecture and power-down mode. The distributed architecture consists of independent converters for maximum power point tracking operation of photovoltaic (PV) panels. This is possible by using gallium nitride field-effect transistors to reduce the converter footprint and placing the converters on the back-side of the PV panels. Also, single-inductor based <inline-formula><tex-math notation="LaTeX">$N$</tex-math></inline-formula>-1 redundant converters for generation and load-side are proposed to provide uninterrupted operation during component failures. Thus, the proposed distributed architecture not only improves the reliability but also facilitates placement of redundant converters to achieve the fault-tolerant capability. To further reduce the electrical and thermal stresses on the semiconductor devices and thus, improve the EPS life span, a novel power-down mode is proposed for the power converters. In this mode, semiconductor devices are switched-<small>off</small> whenever the power processed is below the threshold level and/or no-load operation. Reliability block diagrams are illustrated to demonstrate the reliability improvement and calculations shows that the proposed distributed architecture has higher reliability than the conventional EPS architecture. All the proposed concepts are validated using a prototype developed based on the specifications of MYSAT-1, which is an 1U CubeSat launched by Khalifa University.

Power Electronics Programmable Voltage Source with Reduced Ripple Component of Output Signal Based on Continuous-Time Sigma-Delta Modulator

In this work, an idea of a wideband, precision, power electronics programmable voltage source (PVS) is presented. One of the basic elements of the converter, the control section, contains a continuous-time sigma-delta modulator (SDM) with a pair of interconnected complementary comparators, which represents a new approach. In this case, the SDM uses comparators with a dynamic hysteresis loop (DHC) that includes an AC circuit rather than an R-R network. Dynamic hysteresis is a very effective way of eliminating parasitic oscillation during the signal transition at the input of the comparator; it also affects the frequency characteristics and, especially, the phase properties of the comparator, and this phenomenon is exploited in the proposed converter. The main disadvantage of all pulse-modulated converters is the presence of a ripple component in the output voltage (current), which reduces the quality of the output signal and may cause high-frequency disturbances. A basic feature of PVS is a lower RMS value for the pulse modulation component in the output voltage of the converter, compared to the typical value. Another important feature of the proposed converter is the ability of precise mapping of the output voltage to the reference (input) signal. The structure of the control circuit is relatively simple—no complex, digital components are used. Due to the high frequency of the SDM output bit-stream, the simulation model of the power stage of PVS is based on the power modules with gallium-nitride field effect transistors (GaN FETs). The work discusses the rules of PVS operations and the results from PVS simulation model studies as well as highlights the possible application fields for systems with a PVS.

Gallium-Nitride Field Effect Transistors in Extreme Temperature Conditions

Abstract Compact power electronic circuits and higher operating temperatures of switching devices call for an analysis and verification on the impact of the parasitic components in these devices. The found drift mechanisms in a gallium-nitride field effect transistors (GaN-FET) are studied by literature and related to measurement results. The measurements in extreme temperature conditions are far beyond the manufacturer-recommended operating range. Influences to parasitic elements in both static and dynamic operation of the GaN-FETs are investigated and related toward device losses in switch-mode power electronic circuits with the example of a half-bridge circuit. In this article, static operation investigation on the effect of temperature toward resistance, leakage currents, and reverse conduction is conducted. Dynamic operation between the two states of GaN-FET is also addressed and related to the potential impact in a switching circuit losses. A thermal chamber was built to precisely measure the effect of temperature toward parasitic elements in the devices using a curve tracer. It was found that the increment in RDSon, IDSS, IGSS, and VSD can be justified by the literature and verified by measurements. Incremental COSS and decreasing VGSth was found when exposing devices to extreme temperatures. These two parameters give real challenge over designing circuits at high temperature where timing is critical. Albeit temperature challenges, it is found that investigated GaN-FETs have potential to be used in extreme temperature-operating conditions.

Precise, subnanosecond, and high-voltage switching enabled by gallium nitride electronics integrated into complex loads.

In this work, we report the use of commercial gallium nitride (GaN) power electronics to precisely switch complex distributed loads, such as electron lenses and deflectors. This was accomplished by taking advantage of the small form-factor, low-power dissipation, and high temperature compatibility of GaN field effect transistors (GaNFETs) to integrate pulsers directly into the loads to be switched, even under vacuum. This integration reduces parasitics to allow for faster switching and removes the requirement to impedance match the load to a transmission line by allowing for a lumped element approximation of the load even with subnanosecond switching. Depending on the chosen GaNFET and driver, these GaN pulsers are capable of generating pulses ranging from 100 to 650V and 5 to 60A in 0.25-8ns using simple designs with easy control, few-nanosecond propagation delays, and MHz repetition rates. We experimentally demonstrate a simple 250ps, 100V pulser measured by using a directly coupled 2GHz oscilloscope. By introducing resistive dampening, we can eliminate ringing to allow for precise 100V transitions that complete a -10 to -90V transition in 1.5ns, limited primarily by the inductance of the oscilloscope measurement path. The performance of the pulser attached to various load structures is simulated, demonstrating the possibility of even faster switching of internal fields in these loads. We test these circuits under vacuum and up to 120°C to demonstrate their flexibility. We expect these GaN pulsers to have broad application in fields such as optics, nuclear sciences, charged particle optics, and atomic physics that require nanosecond, high-voltage transitions.

Mechanism of wireless power transfer system waveform distortion caused by nonideal gallium nitride transistor characteristics

Gallium nitride (GaN) field-effect transistors have low ON resistance and switching losses in high-frequency (>MHz) resonant wireless power transfer systems. Nevertheless, their performance in the system is determined by their characteristics and operation mode. A particular operating mode in a 6.78-MHz magnetic resonant wireless transfer system that employs class-D GaN power amplifiers in the zero-voltage switching mode is studied. Two operation modes, the forward mode and the reverse mode, are investigated. The nonideal effect under the device-level dynamic resistance and thermal effect are also analyzed. The dynamic resistance under different operation modes is demonstrated to have different generation mechanisms. Finally, the device characteristics with system operating conditions are combined, and the effects of temperature and dynamic resistance under different operating conditions are evaluated.

Inductive Power Transfer Subsystem for Integrated Motor Drive

An inductive power transfer subsystem for an integrated motor drive is presented in this paper. First, the concept of an integrated motor drive system is overviewed, and its main components are described. Next, the paper is focused on its inductive power transfer subsystem, which includes a magnetically coupled resonant circuit and two-stage energy conversion with an appropriate control method. Simplified complex domain analysis of the magnetically coupled resonant circuit is provided and the applied procedure for its component selection is explained. Furthermore, the prototype of the integrated motor drive system with its control is described. Finally, the prototype based on the gallium nitride field effect transistors (GaN FET) inductive power transfer subsystem is experimentally tested, confirming the feasibility of the concept.

Design and Implementation of a Control Method for GaN-Based Totem-Pole Boost-Type PFC Rectifier in Energy Storage Systems

With the unceasing advancement of wide-bandgap (WBG) semiconductor technology, the minimal reverse-recovery charge Qrr and other more powerful natures of WBG transistors enable totem-pole bridgeless power factor correction to become a dominant solution for energy storage systems (ESS). This paper focuses on the design and implementation of a control structure for a totem-pole boost PFC with newfangled enhancement-mode gallium nitride field-effect transistors (eGaN FETs), not only to simplify the control implementation but also to achieve high power quality and efficiency. The converter is designed to convert a 90–264-VAC input to a 385-VDC output for a 2.6-kW output power. Lastly, to validate the methodology, an experimental prototype is characterized and fabricated. The uttermost efficiency at 230 VAC reaches 99.14%. The lowest total harmonic distortion in the current (ITHD) at high line condition (230 V) attains 1.52% while the power factor gains 0.9985.

Vertical 3D gallium nitride field-effect transistors based on fin structures with inverted p-doped channel

This paper demonstrates the first vertical field-effect transistor based on gallium nitride (GaN) fin structures with an inverted p-doped channel layer. A top-down hybrid etching approach combining inductively coupled plasma reactive ion etching and KOH-based wet etching was applied to fabricate regular fields of GaN fins with smooth a-plane sidewalls. The obtained morphologies are explained using a cavity step-flow model. A 3D processing scheme has been developed and evaluated via focussed ion beam cross-sections. The top-down approach allows the introduction of arbitrary doping profiles along the channel without regrowth, enabling the modulation of the channel properties and thus increasing the flexibility of the device concept. Here, a vertical npn-doping profile was used to achieve normally-off operation with an increased threshold voltage as high as 2.65 V. The p-doped region and the 3D gate wrapped around the sidewalls create a very narrow vertical electron channel close to the interface between dielectric and semiconductor, resulting in good electrostatic gate control, low leakage currents through the inner fin core and high sensitivity to the interface between GaN and gate oxide. Hydrodynamic transport simulations were carried out and show good agreement with the performed current–voltage and capacitance–voltage measurements. The simulation indicates a reduced channel mobility which we attribute to interface scattering being particularly relevant in narrow channels. We also demonstrate the existence of oxide and interface traps with an estimated sheet density of 3.2 × 1012 cm−2 related to the Al2O3 gate dielectric causing an increased subthreshold swing. Thus, improving the interface quality is essential to reach the full potential of the presented vertical 3D transistor concept.

Sparse Kernel Ridge Regression Assisted Particle Filter Based Remaining Useful Life Estimation of Cascode GaN FET

This article proposes a novel sparse kernel ridge regression assisted particle filter (SKRR-PF) based remaining useful life (RUL) estimation method to address the reliability of the cascode gallium nitride field-effect transistors in emerging power electronics systems. The proposed method will overcome three main challenges in this area: first, a large variation in the RUL estimation under the severe noise uncertainty; second, sample degeneracy and sample impoverishment; and third, the low capability of tracing the dynamic and abrupt change in the fault precursor trajectory. The state-of-the-art RUL estimation methods require a significant number of samples to address such issues, including particle degeneracy and sample impoverishment. Also, the state-of-the-art methods mostly fail to apply under a system's dynamic condition changes over a switch's lifetime. The proposed method will significantly enhance the estimation accuracy by introducing SKRR in resampling the posterior probability density function estimation, especially under the dynamically varying system's health condition due to the harsh industrial operation. Thus, the proposed method will offer fast tracing the sudden change in the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,</sub> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> trajectory, leading to a significant accurate RUL estimation. The performance of the proposed method has been rigorously validated through the purposely designed power cycling testbed.

Power Gallium Nitride Technology: The Need for Efficient Power Conversion

The biggest motivation and driver for semiconductor power device innovation is improved efficiency in power conversion. Power gallium nitride (GaN) technology shows the greatest performance benefits against other incumbent technologies, including silicon (Si) technology. A reduction in power losses is the key challenge industries are facing. Pressure from society and government legislation for reduced CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> emission are all trending toward more efficient power conversion and electrification. Automotive electrification, telecom infrastructure, server storage, and industrial automation using power electronics are the biggest trends in the technology sector. GaN field-effect transistors (FETs) can enable us to achieve the best efficiency with lower system costs while making systems lighter, smaller, and cooler. Electrification in the automotive sector can be the biggest beneficiary of this new power GaN FET technology.

Comparative study of gallium nitride and silicon carbide MOSFETs as power switching applications under cryogenic conditions

The operation of power switching systems based on Gallium Nitride (GaN) and Silicon Carbide (SiC) metal oxide field effect transistors (MOSFETs) were presented under the influence of very low temperatures ranging from (−173 °C) up-to (+25 °C). In this concern, the static –and dynamic –characteristic curves were plotted at different temperature levels within the investigated range, where it is clear that, all of the threshold voltage, ON-state resistance, input, output and reverse transfer-capacitances, figure of merit and total gate charge were shown to be decreased with temperature decreasing. Besides, the work was extended to investigate the performance of both devices whenever operates as a switch, where plotting their transient times, showed that, nearly all times of the investigated MOSFET switches are a direct function of temperature.