Gate Current Research Articles

The effect of Lavandula Coronopifolia essential oil on the biophysical properties of desensitization and deactivation gating currents in ionotropic receptors

The rising incidence of cancer and the lack of effective therapeutic interventions for many neurological illnesses like Alzheimer's and epilepsy has prompted us to investigate the composition and effects of the Lavandula coronopifolia oil from Palestine on cancer cells and AMPA receptor subunits in the brain due to the vast range of beneficial properties of Lavandula coronopifolia essential oil (EO). GC/MS was used to analyze L. coronopifolia's EO chemistry. EO's cytotoxicity and biophysical effects on AMPA receptors were investigated using MTS and electrophysiological techniques. The GC–MS results revealed that L. coronopifolia EO has a high content of eucalyptol (77.23%), β-pinene (6.93%), and α-pinene (4.95%). The EO showed more significant antiproliferative selectivity activities against HepG2 cancer cell lines than HEK293T cell lines with IC50 values of 58.51 and 133.22 µg/mL, respectively. The EO of L. coronopifolia affected AMPA receptor kinetics (desensitization and deactivation) and preferred homomeric GluA1 and heteromeric GluA1/A2 receptors. These findings indicate the potential therapeutic use of L. coronopifolia EO in the selective treatment of HepG2 cancer cell lines and neurodegenerative diseases.

Sub‐Band Filling and Hole Transport in Polythiophene‐Based Electrolyte‐Gated Transistors: Effect of Side‐Chain Length and Density

AbstractThe relationship between hole density and conductivity in electrochemically gated polythiophene films is examined. The films are integrated into electrolyte‐gated transistors (EGTs), so that hole accumulations can be electrochemically modulated up to ≈0.4 holes per thiophene ring (hpr). Polythiophenes include poly(3‐alkylthiophenes) (P3ATs) with four different side chain lengths – butyl (P3BT), hexyl (P3HT), octyl (P3OT), or decyl (P3DT) – and poly[2,5‐bis(3‐dodecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (PBTTT) and poly(3,3′′′‐didodecyl[2,2′:5′,2′′:5′′,2′′′‐quaterthiophene]‐5,5′′′‐diyl) (PQT). Analysis of the drain current – gate voltage (ID–VG) and gate current – gate voltage (IG–VG) characteristics of the EGTs reveals that all six polythiophene semiconductors exhibited reversible conductivity peaks at 0.12 – 0.15 hpr. Conductivity is suppressed beyond ≈0.4 hpr.The maximum carrier mobilities of the P3AT semiconductors increase, and hysteresis of the conductivity peaks decreases, with increasing alkyl side‐chain length. PBTTT and PQT with reduced side chain densities exhibit the largest hysteresis but have higher hole mobilities. The results suggest that at ≈0.4 hpr, a polaronic sub‐band is filled in all cases. Filling of the sub‐band correlates with a collapse in the hole mobility. The side‐chain dependence of the peak conductivity and hysteresis further suggests that Coulombic ion‐carrier interactions are important in these systems. Tailoring ion‐carrier correlations is likely important for further improvements in transport properties of electrochemically doped polythiophenes.

Giant electrically tunable magnon transport anisotropy in a van der Waals antiferromagnetic insulator

Anisotropy is a manifestation of lowered symmetry in material systems that have profound fundamental and technological implications. For van der Waals magnets, the two-dimensional (2D) nature greatly enhances the effect of in-plane anisotropy. However, electrical manipulation of such anisotropy as well as demonstration of possible applications remains elusive. In particular, in-situ electrical modulation of anisotropy in spin transport, vital for spintronics applications, has yet to be achieved. Here, we realized giant electrically tunable anisotropy in the transport of second harmonic thermal magnons (SHM) in van der Waals anti-ferromagnetic insulator CrPS4 with the application of modest gate current. Theoretical modeling found that 2D anisotropic spin Seebeck effect is the key to the electrical tunability. Making use of such large and tunable anisotropy, we demonstrated multi-bit read-only memories (ROMs) where information is inscribed by the anisotropy of magnon transport in CrPS4. Our result unveils the potential of anisotropic van der Waals magnons for information storage and processing.

Monitoring Chip Branch Failure in Multichip IGBT Modules Based on Gate Charge

The reliability of the multichip insulated gate bipolar transistor (IGBT) modules has been a concern. Condition monitoring is an effective approach to enhance reliability and improve the quality of customer service. This paper proposes a method for monitoring the chip branch failure due to bond wires fatigue in the multichip IGBT modules. The idea is based on the cumulative effect of the gate charge deviation when the chip branch fails. By integrating the turn-on gate current of multiple switching cycles, the health state of multichip IGBT modules is characterized by the capacitor voltage as a health-sensitive parameter that can be extracted in the proposed monitoring circuit integrated into the gate driver. The capacitor voltage decreases significantly when the chip branch occurs due to bond wires fatigue. It is stable during sampling and has a strong immunity to junction temperature, collector current, and collector-emitter voltage. Besides, the method is non-intrusive and has the potential for real-time and online monitoring. These characteristics make the method reliable, easy to implement, and convenient for health status identification. The confirmatory experiment is carried out to verify the feasibility of the method.

Improved drain lag by reduced surface current in GaN HEMT via an ultrathin HfO2 blanket layer

This paper reports the influence of an ultrathin 1.5 nm atomic-layer-deposited HfO2 blanket layer as a gate dielectric on GaN high-electron-mobility transistors (HEMTs) grown on a 4H-SiC substrate. Transistors with a gate length of 250 nm and a source-to-drain distance of 3 µm were manufactured. The proposed technique involves HfO2 deposition at 250 ∘C prior to the gate metallization with no additional lithography steps. This approach reduced the drain lag by 83% compared to the conventional design with no gate dielectric. The HfO2 layer suppressed the parasitic lateral conduction from the gate, reduced surface trapping, and improved gate electrostatics. The manufactured devices exhibited nearly three orders of magnitude decreased surface leakage, better turn-on behavior, and improved cut-off frequency f T linearity by 16%. High quality metal-oxide interface formation was confirmed by the conductance method. Results demonstrate that the blanket HfO2 deposition is a promising approach to improve the current dispersion characteristics and gate electrostatics of GaN HEMTs without incurring major changes to the established fabrication techniques.

Monitoring chip-branches failure of multichip IGBT module using change rate of gate voltage

In order to increase system reliability, it is an economical and efficient method to monitor the defective multichip insulated gate bipolar transistor (IGBT) modules, which are widely used in various high-power electronic systems. A method is presented to monitor chip-branches failure caused by bond-wires defects inside the multichip IGBT modules when the modules are in the off-state. It is based on that the gate input capacitance of the multichip IGBT module will be changed by the failure of chip branches caused by bond-wires defects. The change rate of gate voltage under the constant gate current can be used to characterize the failure. Firstly, according to the gate charge characteristics, the relationship between the change rate of gate voltage and the chip-branches failure under the constant gate current is given. The process of monitoring chip-branches failure is described. Then, a gate driver is presented, which contains a constant current source, and the feasibility of the monitoring method is verified. The study results show that under the constant current source driver and within the specific range of gate voltage, the change rate of gate voltage is independent of temperature and collector–emitter voltage, only related to the failure of chip branches due to bond-wires defects in the multichip IGBT module and increases significantly with the chip-branches failure. Finally, the characteristics of this method are analyzed by comparison with other similar condition monitoring methods. This method is easy to measure and can be applied to the case of real-time and online monitoring.

Deep sub-60 mV/dec subthreshold swing independent of gate bias sweep direction in an in situ SiN/Al0.6Ga0.4N/GaN-on-Si metal-insulator high electron mobility transistor

In this Letter, we demonstrated deep sub-60 mV/dec subthreshold swings (SS) independent of gate bias sweep direction in GaN-based metal–insulator–semiconductor high electron mobility transistors (MISHEMTs) with an Al0.6Ga0.4N/GaN heterostructure and in situ SiN as gate dielectric and surface passivation. Average SS values of 22 and 29 mV/dec over 3–4 orders of drain current (ID) swing were measured during forward and reverse sweeps, respectively, in a 75-nm gate length (LG) device. Sub-60 mV/dec SS was also observed in the GaN MISHEMTs with longer LG up to 350 nm. The intrinsic physical mechanisms of deep sub-60 mV/dec SS were comprehensively studied. The observed negative differential resistance in the gate current, the kinks in the output ID-VD curve, and the capacitance spike in the depletion region of the C–V curves suggest that the capture and emission of electrons in the traps are the dominant physical mechanisms responsible for the small SS.

Neural Network-Based BSIM Transistor Model Framework: Currents, Charges, Variability, and Circuit Simulation

We present a neural network (NN)-based transistor modeling framework, which includes drain, source, and gate currents and charges and their variabilities. The training data are generated by a Berkeley short-channel IGFET model (BSIM) with ranges of channel lengths, widths, and oxide thicknesses. The NNs are trained to learn the geometry dependence. The drain, source, and gate currents are modeled with one NN and the charges by another NN. The NNs are trained to produce accurate variability prediction and derivatives of currents and charges. Quality and robustness tests, such as Gummel symmetry, harmonic balance, and ring oscillator, are performed and show excellent results.

High-threshold-voltage and low-leakage-current of normally-off H-diamond FET with self-aligned Zr/ZrO2 gate

Normally-off field effect transistor (FET) is highly required for the safe and energy-efficient operation of power switching system. The hydrogen-terminated diamond (H-diamond) FET possesses outstanding properties whereas it usually shows normally on operation. In this paper, high-threshold-voltage and low-leakage-current of normally-off H-diamond FET was achieved via ZrO2/Zr gate fabricated by thermal oxidation (TO) with merits of non-pollution and simple process. The normally-off operation owed to the work function difference between Zr and H-diamond and the positive fixed charge of ZrO2. The X-ray photoelectron spectroscopy results reveal the ZrO2/Zr gate structure and the stoichiometric composition of Zr to O (1:2). The high threshold voltage (−2.7 V) and low drain-source leakage current (10−8 mA/mm) may be attributed to the Schottky barrier of Zr/H-diamond. Additionally, the gate leakage is suppressed by TO-ZrO2. The subthreshold swing, on-off current ratio and gate oxide capacitance per square centimeter are 161 mV/dec, 108 and 0.37 μF/cm2, respectively. These performances demonstrate that the ZrO2/Zr/H-diamond FET would provide an alternative approach for low power H-diamond FET.

Investigation of trap characteristics under the inverse piezoelectric effect in AlGaN/GaN HEMT devices at room temperature and low temperature

Changes in the electrical properties and the trap characteristics of AlGaN/GaN high electron mobility transistors under the application of reverse bias stress at both room temperature and low temperature were investigated. When the critical stress voltage was reached, the gate current, which complied with the Poole–Frenkel conduction conditions, showed an abrupt increase. Furthermore, the magnitude of the critical stress voltage for occurrence of the inverse piezoelectric effect can be increased at 83 K. The transient current method was used to establish that the detrapping peak amplitudes of the traps increased, but the trap activation energy remained unchanged. The changes observed in both the time constant spectra and the pulsed current–voltage curves confirmed that the trap densities in the AlGaN barrier layer increased as a result of the inverse piezoelectric effect. However, the different degrees to which the numbers of traps increased at room temperature and at 83 K contributed to the occurrence of different degradations in the device.

Characterization of two pathological gating-charge substitutions in Cav1.4 L-type calcium channels

ABSTRACT Cav1.4 L-type calcium channels are predominantly expressed at the photoreceptor terminals and in bipolar cells, mediating neurotransmitter release. Mutations in its gene, CACNA1F, can cause congenital stationary night-blindness type 2 (CSNB2). Due to phenotypic variability in CSNB2, characterization of pathological variants is necessary to better determine pathological mechanism at the site of action. A set of known mutations affects conserved gating charges in the S4 voltage sensor, two of which have been found in male CSNB2 patients. Here, we describe two disease-causing Cav1.4 mutations with gating charge neutralization, exchanging an arginine 964 with glycine (RG) or arginine 1288 with leucine (RL). In both, charge neutralization was associated with a reduction channel expression also reflected in smaller ON gating currents. In RL channels, the strong decrease in whole-cell current densities might additionally be explained by a reduction of single-channel currents. We further identified alterations in their biophysical properties, such as a hyperpolarizing shift of the activation threshold and an increase in slope factor of activation and inactivation. Molecular dynamic simulations in RL substituted channels indicated water wires in both, resting and active, channel states, suggesting the development of omega (ω)currents as a new pathological mechanism in CSNB2. This sum of the respective channel property alterations might add to the differential symptoms in patients beside other factors, such as genomic and environmental deviations.

Experimental study of venting efficiency of salinity current

ABSTRACT The dam is one of the most prominent hydraulic constructions on the world. Sediment flows into dam reservoirs because of human involvement in the dam catchment region, eventually affecting its functional storage. Density currents are a key feature of sedimentation. The use of bottom outflow gates to preserve the reservoir’s usable volume is one approach of mitigating the effects of sedimentation. This could have an effect on the quality of the water as it exits the dam. The purpose of this research was to see how well salt current from lock exchanges was vented at different levels and outlet gate sizes. Based on the latest study’s experiments, this is the highest venting efficiency when the location of outlets is in the quarter of the bottom of the dam. The output concentration will be equal to the average concentration of the concentrated input current, which is the best height for installing the outlet gates, based on the maximum venting efficiency demonstrated in the recent study’s experiments, which may be described as the best height for the turbidity current outlet gate. Discharge efficiency increases when the intake concentration is lower.

Demonstration of the β-Ga₂O₃ MOS-JFETs With Suppressed Gate Leakage Current and Large Gate Swing

In this work, we have achieved novel lateral enhancement-mode (E-M) and depletion-mode (D-M) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 metal-oxide-semiconductor junction field-effect- transistors (MOS-JFETs) featuring a low gate leakage current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{{\text {G}}}$ </tex-math></inline-formula> ) and a large gate swing. Ascribing to the high-quality SiO2 layer above the P-NiO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{{\text {X}}}}$ </tex-math></inline-formula> /N-Ga2O3 heterojunction (HJ), the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{G}$ </tex-math></inline-formula> was suppressed for over 6 orders of magnitudes when compared with the heterojunction FET (HJ-FET). An off-state drain current of ~ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-{7}}$ </tex-math></inline-formula> mA/mm was also achieved at elevated temperature (T) up to 200 °C, indicating strong thermal stability of our device. The depletion-mode (D-M) MOS-JFET with source-to-drain spacing ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{L}_{{\text {SD}}}$ </tex-math></inline-formula> ) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12 ~\mu \text{m}$ </tex-math></inline-formula> demonstrates a breakdown voltage (BV) of 1.32 kV and specific on-resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{R}_{{\text {on},\text {sp}}}$ </tex-math></inline-formula> ) of 4.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2, delivering a high Baliga’s power figure of merit (PFOM) of 405 MW/cm2. Due to the potential of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> -Ga2O3 MOS-JFET in power electronics, these findings offer a compel ling pathway for future high-power and high-efficiency systems.

Tuning the temperature dependence of Shaker potassium channel with mutations at S4-S5 linker.

We investigated the effects of temperature on mutations that uncouple the voltage sensor (VSD) from the pore (PD) in the Shaker-IR potassium channel using temperature step (Tstep). We utilized a setup that achieves fast temperature changes (millisecond) and allows the recording of the cell membrane temperature with sub-millisecond resolution (https://doi.org/10.1101/2022.07.11.499616). We used the mutants V369I, I372L, S376T (ILT), in the N-terminus of the S4-S5, that produces a split in the components of the gating charge movement, and I384N, near the S4-S5 C-terminus, that uncouples the VSD charge movement from the PD. From a bath temperature of 17 ºC, we used a Tstep of around ∼9 ºC with rising phase of 1.5 ms. In ILT, applying a Tstep, after the gating currents have subsided, promotes a right shift in the first component of gating charge and a left shift of the second component (the last concerted step associated with PD opening). Consistently, Tstep applied after the onset of a depolarizing voltage pulse produces a ∼5 mV left shift in the conductance-voltage curve (G-V). The entropy, calculated from G-V, changes from 24 for WT to −42 J/K for ILT. In I384N, applying a Tstep reduces the ionic current indicating the closure of the pore. We hypothesize that the temperature dependence of the ILT G-V arises from the changes in the last step of the charge movement. On the other hand, since the VSD and PD are loosely coupled in I384N, the increase in temperature is likely to further decrease the VSD-PD coupling, thus decreasing the measured conductance. (Support: NIH: GM030376, Fondecyt: 1190203)

High-level expression of voltage-gated sodium channels in thymidine-arrested human embryonic kidney cells.

The benefit of using heterologous mammalian cell lines such as human embryonic kidney (HEK293) cells for expressing voltage-gated ion channels includes efficient translation and processing of such large membrane proteins. Still, the biophysical assessment of these channels is hindered by their low expression and reduced localization on the surface of a cell. Having a higher expression level of ion channels is crucial for investigating mutations that cause a decrease in the current amplitude as well as for measuring tiny currents such as gating currents and gating pore currents that are in the range of 0.1 to 1% of the peak current. We aimed at improving the efficiency of ion channel expression and enhancing their localization in cell membranes by modifying the protocol of cell cycle arrest at the G1/S boundary using thymidine to direct the cells into increasing the expression machinery during viral transduction of mammalian voltage-gated sodium channels. The combination of cell arrest at the G1/S boundary and mammalian baculovirus system (BacMam) resulted in a 5-fold increase in the current density of different mammalian voltage-gated sodium channels in HEK293 cells compared to the current literature. By applying this modified protocol for expression, we succeeded to measure a pathogenic gating pore current in HEK293 cells of ∼0.5% of the central pore current induced by an autism-related mutation in the R2 gating charge in Domain II (R853Q) of Nav1.2, which is blocked in a voltage-dependent manner when the voltage sensors activate. These results show that our protocol is a universal one that can be applied on different voltage-gated ion channels and possibly other membrane proteins. This ultimately will pave the way to decipher the structure and function of ion channels and their association with ion channelopathies and other diseases.

Fine-structure constant and hysteresis regimes in the giant squid propagating action potential.

We present a phase space based phenomenological theory for the steady propagation of the action potential using the Rosenthal-Bezanilla experimental data. Time derivatives of giant squid action potential, its velocity of propagation, the radius of the axon and its capacitance, and the resistivity of axoplasm, yield the total ionic, capacitive, and membrane currents of the charge conserving cable equation. Evidence is presented that the sodium channels lattice has a polarization flip at the inception of the action potential and the corresponding flip reversal at the peak of the action potential while traversing a ferroelectric hysteresis loop. The polarization flip at the inception of the action potential is followed by capacitive polarization current known as gating current. The polarization flip at the peak of the action potential is preceded by a small sodium polarization current associated with sodium current inactivation. Ionic currents and sodium polarization ionic currentsare taken to have the familiar structure, as the product of maximum conductance, driving force, and fraction of open channels. Fractions of open channels are fitted in the lab frame by modified Avrami equations seeded with the value of the fine-structure constant α = 0.0072973... . The existence of sodium channels domains with two different symmetries, albeit only one being stable in squid axon, suggests the possibility of neurons with at least 2 stable states, the necessary condition for storage and retrieval of memories. It is expected that presented results will provide the framework for further analysis of thermodynamic phase changing behavior, the role of quantum mechanics in the flow of ions trough ionic channels and in particular the role of ferroelectric sodium channels lattice behavior in storage and retrieval of memories and nerve excitability.

Cryo-EM structure of the mammalian Kv2.1 channel and epileptic encephalopathy mutations provide insight into electromechanical coupling and slow inactivation.

The Kv2.1 delayed-rectifier K+ channel is one of the most abundant ion channels in the mammalian brain, where it is critical for neuronal activity, with mutations in humans causing epileptic encephalopathies. Kv2.1 opens slowly in response to membrane depolarization and slowly inactivates on the timescale of seconds. Slow inactivation in Kv2.1 is not sensitive to several manipulations that strongly influence C-type inactivation in Kv1 channels, including raising the concentration of external K+, external blockers such as tetraethylammonium (TEA) and mutations in the external pore near the ion selectivity filter. We solved the cryo-EM structure of Kv2.1 at 2.9-Å resolution, which reveals that the protein adopts an overall fold that is similar to Kv1 channels. Mutations causing epileptic encephalopathies are distributed throughout the structure of the transmembrane region of Kv2.1, producing distinct alterations in voltage-dependent activation. One particularly interesting epileptic encephalopathy mutant of a Phe to Leu near the internal end of the S6 pore-lining helix, rendered the channel effectively non-conducting; gating currents arising from activation of the voltage sensors could be measured without any evidence of ion conduction. From the cryo-EM structure, we identified a cluster of three Leu residues that interact intimately with the Phe, and when mutated to Ala remained conducting but with greatly accelerated (10-100-fold) slow inactivation. Experiments using internal TEA to detect opening of the internal gate in the non-conducting mutant of Kv2.1 suggest that the internal gate remains closed. From these and other findings, we propose that slow inactivation in Kv2.1 involves electromechanical coupling between the voltage sensors and pore, with reclosure of the internal gate occurring while the voltage sensors remain activated.

Activation-pathway transitions in human voltage-gated proton channels revealed by a non-canonical fluorescent amino acid.

Voltage-dependent gating of the voltage-gated proton channels (HV1) remains poorly understood, partly because of the difficulty of obtaining direct measurements of voltage sensor movement in the form of gating currents. To circumvent this problem, we have implemented patch-clamp fluorometry in combination with the incorporation of the fluorescent non-canonical amino acid Anap to monitor channel opening and movement of the S4 segment. Simultaneous recording of currents and fluorescence signals allows for direct correlation of these parameters and investigation of their dependence on voltage and the pH gradient (ΔpH). We present data that indicate that Anap incorporated in the S4 helix is quenched by an aromatic residue located in the S2 helix and that motion of the S4 relative to this quencher is responsible for fluorescence increases upon depolarization. The kinetics of the fluorescence signal reveal the existence of a very slow transition in the deactivation pathway, which seems to be singularly regulated by ΔpH. Our experiments also suggest that the voltage sensor can move after channel opening and that the absolute value of the pH can influence the channel opening step. These results shed light on the complexities of voltage-dependent opening of human HV1 channels.

Modeling the Effects of Threading Dislocations on Current in AlGaN/GaN HEMT

The aim of this paper is to model the effects of threading dislocations on both gate and drain currents of AlGaN/GaN high electron mobility transistors (HEMTs). The fraction of filled traps increases with the threading dislocations, while the trapping effects cause a decrease in drain current and an increase in gate leakage current. To model the drain current drop, the two simplified RC subcircuits with diodes are proposed to capture the charge trapping/detrapping characteristics. The trap voltages Vg_trap and Vd_trap generated by RC networks are fed back into the model to capture the effects of traps on drain current. Considering acceptor-decorated dislocations, we present a novel Poole-Frenkel (PF) model to precisely describe the reverse leakage gate current, which plays a dominant role in the gate leakage current. The proposed model, which uses physical parameters only, is implemented in Verilog-A. It is in excellent agreement with the experimental data.

Polarization induced doping and high-k passivation engineering on T-gate MOS-HEMT for improved RF/microwave performance

High electron-mobility transistors (HEMTs) based on III-nitrides are well-known as ideal choices for high-power, radio-frequency applications. HEMTs, on the other hand, must deal with the critical issues of the large gate and buffer leakage currents, which unavoidably restrict device performance and reliability. Here, we use HfO2 as a gate dielectric to mimic an InAlN/AlN meta-oxidesemiconductor high electron mobility transistor (MOS-HEMT) that can enhance the interfacial and transport characteristics and reduce the gate leakage current. Furthermore, polarization-induced doping in the buffer region is also implemented, enhancing the two-dimensional electron gas confinement by bending the conduction band upwardly convex, effectively reducing the buffer leakage current, and enhancing the breakdown voltage (35 V). The implementation of the above two engineerings significantly enhances the gain maximum oscillation frequency (246 GHz) and cut-off frequency (156 GHz). The simulated results of the proposed device design show its applicability for high RF/microwave applications.