Turn-on Characteristics Research Articles

Ultralow-Power Circuit and Sensing Applications Based on Subthermionic Threshold Switching Transistors.

The most recent breakthrough in state-of-the-art electronics and optoelectronics involves the adoption of steep-slope field-effect transistors (FETs), promoting sub-60 mV/dec subthreshold swing (SS) at ambient temperature, effectively overcoming "Boltzmann limit" to minimize power consumption. Here, a series integration of nanoscale copper-based resistive-filamentary threshold switch (TS) with the IGZO channel-based FET is used to develop a TS-FET, in which the turn-on characteristics exhibit an abrupt transition over five decades, with an extremely low SS of 7 mV/dec, a high on/off ratio (>109), and ultralow leakage current (40-fold decrease), ensuring excellent repeatability and device yield. Unlike previous device-centric studies, this work highlights potential circuit applications (logic-inverter, pulse-sensor amplification, and photodetector) based on TS-FET. The sharp transition behavior of TS-FET enables the establishment of logic inverters with a high voltage gain of ≈800, with a circuit-level demonstration achieving a bias-independent record-high intrinsic gain (>1000). A wearable pulse sensor integrated with an amplifier circuit ensured the precise amplification of electrophysical signals by 450 times. In addition, the application of a TS-FET-based photodetector features high responsivity (1.08 × 104 mA/W) and detectivity (1.03 × 1020 Jones). The low-power strategy of TS-FETs is promising for the development of energy-efficient integrated circuits alongside sensor-interconnected biomedical applications in wearable technology.

Scalable on-chip multiplexing of silicon single and double quantum dots

Owing to the maturity of complementary metal oxide semiconductor (CMOS) microelectronics, qubits realized with spins in silicon quantum dots (QDs) are considered among the most promising technologies for building scalable quantum computers. For this goal, ultra-low-power on-chip cryogenic CMOS (cryo-CMOS) electronics for control, read-out, and interfacing of the qubits is an important milestone. We report on-chip interfacing of tunable electron and hole QDs by a 64-channel cryo-CMOS multiplexer with less-than-detectable static power dissipation. We analyze charge noise and measure state-of-the-art addition energies and gate lever arm parameters in the QDs. We correlate low noise in QDs and sharp turn-on characteristics in cryogenic transistors, both fabricated with the same gate stack. Finally, we demonstrate that our hybrid quantum-CMOS technology provides a route to scalable interfacing of a large number of QD devices, enabling, for example, variability analysis and QD qubit geometry optimization, which are prerequisites for building large-scale silicon-based quantum computers.

Junction-Controlled-Diode-Embedded SiC-MOSFET for Improving Third Quadrant and Turn-On Characteristics

In this paper, we propose a novel 1200V SiC MOSFET featuring the embedded junction-controlled-diode (JCD-MOSFET) and demonstrate its static and dynamic characteristics through TCAD simulations. Without sacrificing blocking and conduction performance, the adoption of JCD can effectively reduce knee voltage to 1.7V based on unipolar carrier conduction mode. Due to the reduced peak reverse recovery current and reverse recovery charge, the JCD-MOSFET achieves 30.8% lower turn-on losses than conventional MOSFET. Meanwhile, the fabrication process for the JCD-MOSFET is the same as conventional MOSFET without an extra mask. This proposed JCD-MOSFET prototype shows great potential in target applications in the near future.

Transient turn-on characteristics of Si RBDT and SiC MOSFET under nanosecond current pulse range

With the development of pulse power supplies, solid-state semiconductor switches are required to have fast switching speeds and low losses. Both Reverse blocking diode thyristor (RBDT) and silicon carbide metal oxide semiconductor field effect transistor (SiC MOSFET) have fast turn-on speed, making them suitable candidates for short pulse generator. In this paper, the transient turn-on characteristics of Si RBDT and SiC MOSFET are analyzed theoretically and validated experimentally. Si RBDT and commercial 1.2 kV/81A SiC MOSFET are comparatively investigated in switching current pulse with a rise time of several hundreds of nanoseconds. (1) The anode current of RBDT could rise exponentially because of the latch-up effect of Si RBDT, while the drain current of SiC MOSFET tends to be saturated. (2) Utilizing the current rise time (Trise) to represent the switching speed, SiC MOSFET can switch faster when the current is lower than 400A. With the increase of the current, Si RBDT presents faster turn-on speed and lower switching loss due to the regenerative action of the two coupled transistors. (3) The transient characteristics of Si RBDT include a voltage-controlled inductance, while SiC MOSFET contains a current-controlled inductance based on the current rise time, respectively. With the increasing of the main voltage, the equivalent inductance of Si RBDT decreases and tends to be saturated when the main voltage is higher than half of the breakdown voltage of Si RBDT. For SiC MOSFET, the equivalent inductance increases until the drain current remains stable for a given gate voltage. This paper confirms the advantages of Si RBDT and SiC MOSFET in different situations.

Steep-slope vertical-transport transistors built from sub-5 nm Thin van der Waals heterostructures

Two-dimensional (2D) semiconductor-based vertical-transport field-effect transistors (VTFETs) – in which the current flows perpendicularly to the substrate surface direction – are in the drive to surmount the stringent downscaling constraints faced by the conventional planar FETs. However, low-power device operation with a sub-60 mV/dec subthreshold swing (SS) at room temperature along with an ultra-scaled channel length remains challenging for 2D semiconductor-based VTFETs. Here, we report steep-slope VTFETs that combine a gate-controllable van der Waals heterojunction and a metal-filamentary threshold switch (TS), featuring a vertical transport channel thinner than 5 nm and sub-thermionic turn-on characteristics. The integrated TS-VTFETs were realised with efficient current switching behaviours, exhibiting a current modulation ratio exceeding 1 × 108 and an average sub-60 mV/dec SS over 6 decades of drain current. The proposed TS-VTFETs with excellent area- and energy-efficiency could help to tackle the performance degradation-device downscaling dilemma faced by logic transistor technologies.

A 2.8 kV Breakdown Voltage α-Ga2O3 MOSFET with Hybrid Schottky Drain Contact.

Among various polymorphic phases of gallium oxide (Ga2O3), α-phase Ga2O3 has clear advantages such as its heteroepitaxial growth as well as wide bandgap, which is promising for use in power devices. In this work, we demonstrate α-Ga2O3 MOSFETs with hybrid Schottky drain (HSD) contact, comprising both Ohmic and Schottky electrode regions. In comparison with conventional Ohmic drain (OD) contact, a lower on-resistance (Ron) of 2.1 kΩ mm is achieved for variable channel lengths. Physics-based TCAD simulation is performed to validate the turn-on characteristics of the Schottky electrode region and the improved Ron. Electric-field analysis in the off-state is conducted for both the OD and HSD devices. Furthermore, a record breakdown voltage (BV) of 2.8 kV is achieved, which is superior to the 1.7 kV of the compared OD device. Our results show that the proposed HSD contact with a further optimized design can be a promising drain electrode scheme for α-Ga2O3 power MOSFETs.

Impact of Temperature on Turn-On Characteristics of Avalanche Transistors and Output Pulses of Their Marx Circuits

Impact of Temperature on Turn-On Characteristics of Avalanche Transistors and Output Pulses of Their Marx Circuits

Towards ultralow-power and high-speed electronics: Tunnel transistor based on single-chain Tellurium

The application of tunnel field-effect transistors (TFETs) in the sub-5.1 nm range meets the challenges of low on-state current (Ion), elevated leakage current (Ileak) and a limited bias range with sub-thermionic subthreshold swing (SS) characteristics. Here, by the design of gate-all-around (GAA) single-chain Te (1Te) TFETs, the sub-thermionic SS characteristics span nearly six orders of magnitude of drain current, overcoming the above challenges. While there usually exists trade-offs between maximizing Ion and minimizing Ileak, our optimized 5.1 nm GAA 1Te TFET defies this convention. Its steep turn-on characteristics result in an ultra-low Ileak of 7.9 × 10−10 μA/μm coupled with a high Ion of 1352 μA/μm, surpassing other low-dimensional materials-based FETs. These exceptional performances are attributed to the desirable properties from ultra-thin 1Te, including its moderate bandgap, anisotropic effective mass, and reduced screening length. Crucially, this device demonstrates key figure of merits for digital electronics that fulfill both the requirements of high-performance and low-power device specified by the International Technology Roadmap for Semiconductors, indicating the potential as energy-efficient and high-speed electronic switch. Our findings are expected to stimulate further research into sub-5.1 nm quasi-1D materials-based TFETs and provide valuable insights for optimizing their performance.

Demonstration of a 4.32 μ m cutoff InAsSbBi nBn photodetector, a lattice-matched random alloy III–V solution for mid-wave infrared sensing

InAsSbBi nBn photodetectors are demonstrated that are lattice-matched to the underlying GaSb substrate with a 4.32 μm wavelength cutoff at 150 K that is 0.3 μm longer than that of lattice-matched InAsSb at this temperature reflecting a 0.5% Bi mole fraction in the InAsSbBi active region. A low growth temperature was utilized to facilitate the incorporation of Bi, resulting in a minority carrier lifetime on the order of 24 ns in the InAsSbBi active region. Nevertheless, the detectors exhibit a quantum efficiency of 17% at 3.3 μm wavelength with a dark current density of 50 μA/cm2 at 150 K and −0.4 V bias and the strong photoresponse turn-on characteristic of a random alloy at 4.32 μm wavelength and 150 K. A shot noise-equivalent irradiance analysis indicates that this detectors' dark-current-limited noise-equivalent irradiance of 1012 cm−2 s−1 is two orders of magnitude greater than the Rule 07 expectation for this cutoff, and dark-current-limited shot noise-equivalent irradiance performance transitions to photon-limited at 1.7 × 1015 photons/cm2 s.

Improving dynamic characteristics for IGBTs by using interleaved trench gate

A novel trench insulated gate bipolar transistor (IGBT) with improved dynamic characteristics is proposed and investigated. The poly gate and poly emitter of the proposed IGBT are arranged alternately along the trench. A self-biased p-MOSFET is formed on the emitter side. Owing to this unique three-dimensional (3D) trench architecture, both the turn-off characteristic and the turn-on characteristic can be greatly improved. At the turn-off moment, the maximum electric field and impact ionization rate of the proposed IGBT decrease and the dynamic avalanche (DA) is suppressed. Comparing with the carrier-stored trench gate bipolar transistor (CSTBT), the turn-off loss (E off) of the proposed IGBT also decreases by 31% at the same ON-state voltage. At the turn-on moment, the built-in p-MOSFET reduces the reverse displacement current (I G_dis), which is conducive to lowing dI C/dt. As a result, compared with the CSTBT with the same turn-on loss (E on), at I C = 20 A/cm2, the proposed IGBT decreases by 35% of collector surge current (I surge) and 52% of dI C/dt.

Diode-Assisted Gate-Commutated Thyristor for Hybrid MVDC Circuit Breaker Applications

This paper presents a Hybrid Circuit Breaker for Medium Voltage Direct Current grids, consisting of an ultra-fast mechanical breaker and a parallel Diode-Assisted Gate-Commutated Thyristor. This device is a GCT based devices, especially developed for this application. It has a higher current interruption capability than commercial IGCTs and a more robust, power-efficient and faster gate drive unit. We designed a stray inductance optimized package with an integrated gate drive unit for the Diode-Assisted Gate-Commutated Thyristor and included diodes with a very high forward voltage drop, which were radiated especially for use in a Diode-Assisted Gate-Commutated Thyristor, to increase its current turn-off capability. The build prototype can interrupt fault currents of 10 kA. An analysis of the stray elements in the package showed a possible increase of the current interruption capability to xy. We analysed the boundary conditions for potential use in an Hybrid Circuit Breaker by investigating the turn-on and turn-off characteristics of the device embedded in a diode full bridge and including a snubber capacitor.

Study on Transient Turn-On Characteristics of Pulse Power Thyristor-Type Devices Under Ultrahigh di/dt Condition

Specially optimized thyristor-type devices for fast turn-on and high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> capability are promising in pulse power applications. In this work, the transient turn-on characteristics of MOS-gate triggered and current-gate triggered thyristor-type devices operating at ultrahigh <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> conditions are first studied. The injected charge transport process is theoretically analyzed and modeled by considering the effect of the transient electric field, during short pulse duration, which then clearly reveals the difference between the MOS-gate triggered and current-gate triggered thyristor-type devices on the transient turn-on characteristics. TCAD simulations and experimental measurements are carried out to verify the transient turn-on process. The theoretical, simulated, and experimental results show that the MOS-gate triggered thyristor has better turn-on characteristics than the current-gate triggered thyristor, which attributes to the reduced turn-on step and consequently stronger conductivity modulation. This work helps further optimization of thyristor-type devices achieving fast turn-on and high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}{i}/\text{d}{t}$ </tex-math></inline-formula> capability.

Effects of Short Pulse on Lateral Current Spreading in Turn-on Process of Pulsed Thyristors Under Inductive Load

Pulsed thyristors widely used in pulsed power generators are more easily confronted with damage problems in the turn-on process due to insufficient lateral current spreading under short pulses. This study aims to explore the spatial and temporal characteristics of the lateral current spreading under short pulses and reveal the relationship between the lateral current spreading and the external circuit with inductive load. Based on turn-on characteristics experiments of a thyristor with an amplifying gate and emitter shorts, mixed semiconductor device, and circuit simulations were carried out to compute the variation of current density in the thyristor under a ten-microsecond pulse. The results show that the current spreads incompletely under 17 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> pulse due to the external circuit and the emitter short. For comparison, the current can continue spreading at the back of the first emitter short as the pulsewidth is 150 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> . The relationship between the current lateral spreading and the external circuit with inductive load under short pulses is established, and a necessary condition for the current to spread at the back of the first emitter short is proposed.

Ultrasmall PtAu2 nanoclusters activate endogenous anti-inflammatory and anti-oxidative systems to prevent inflammatory osteolysis.

Rationale: Inflammatory osteolysis, characterized by abundant immune cell infiltration and osteoclast (OC) formation, is a common complication induced by bacterial products and/or wear particles at the bone-prosthesis interface that severely reduces long-term stability after implantation. Molecular nanoclusters are ultrasmall particles with unique physicochemical and biological properties that have great potential as theranostic agents for treating inflammatory diseases. Methods: In this study, heterometallic PtAu2 nanoclusters with sensitive nitric oxide-responsive phosphorescence turn-on characteristics and strong binding interactions with cysteine were designed, making them desirable candidates for the treatment of inflammatory osteolysis. Results: PtAu2 clusters exhibited satisfactory biocompatibility and cellular uptake behavior, with potent anti-inflammatory and anti-OC activities in vitro. In addition, PtAu2 clusters alleviated lipopolysaccharide-induced calvarial osteolysis in vivo and activated nuclear factor erythroid 2-related factor 2 (Nrf2) expression by disrupting its association with Kelch-like ECH-associated protein 1 (Keap1), thereby upregulating the expression of endogenous anti-inflammatory and anti-oxidative products. Conclusion: Through the rational design of novel heterometallic nanoclusters that activate the endogenous anti-inflammatory system, this study provides new insights into the development of multifunctional molecular therapeutic agents for inflammatory osteolysis and other inflammatory diseases.

N4-phenylquinazoline-4,6-diamine as a tunable fluorescent scaffold for the development of fluorescent probes

Fluorescent molecules have been used for various applications in biological system monitoring. Considering the complexity of cellular systems, there is a huge demand for diverse fluorescent organic molecular scaffolds. However, only a limited number of fluorescent scaffolds have been reported due to the lack of a rational design strategy. We serendipitously discovered N4-phenylquinazoline-4,6-diamine as a fluorescent scaffold with turn-on characteristics. To improve the photophysical property of the initial fluorescence molecule, we synthesized derivatives of the N4-phenylquinazoline-4,6-diamine and found systematic correlation between electronic density of the phenyl substituent of the scaffold and fluorescence intensity. Through tuning the photophysical property of the scaffold and a rational design strategy, we developed N4-dichlorophenylquinazoline-4,6-diamine as a potential fluorophore for various biological applications. To prove the value of the developed fluorescent scaffold, we devised formaldehyde (FA) fluorescent sensor by tailoring amine on 6-position of N4-dichlorophenylquinazoline-4,6-diamine to employ a 2-aza-Cope rearrangement as the molecular detection mechanism with double-digit nanomolar detection limits. FA level in live HeLa cells were successfully visualized with the probe, exhibiting that N4-dichlorophenylquinazoline-4,6-diamine can serve as a useful molecular scaffold for offering various fluorescent sensors toward the investigation of physiological and pathological processes in live cells.

Modeling and Analysis of SiC GTO Thyristor’s Dynamic Turn-On Transient

The fast turn-on speed of silicon carbide (SiC) gate-turn-off (GTO) thyristor is preferred for pulse power applications. However, the turn-on delay phenomenon hinders its improvement. In this article, the dynamic turn-on transient process of SiC GTO thyristor is investigated and analyzed extensively by means of both numerical simulation and physical modeling. The physical mechanism behind its turn-on transient process is discussed in detail. A physical model based on the charge-control theory is proposed to identify the dominant factors influencing the dynamic turn-on transient. Then the theoretical analysis is quantitatively made on the parameter design of GTO’s unit cell, and methods to increase the turn-on switch speed are extensively discussed. This study provides not only in-depth physical insights into the device’s turn-on characteristics, but also designs guidelines for the advancement of SiC GTO thyristor.

Analysis of Impact Ionization Effects on Current Collapse of AlGaN/GaN HEMTs

Computer-aided analysis of impact ionization effects on turn-on characteristics or current collapse of AlGaN/GaN HEMTs is performed. Here, an intrinsic semi-insulating buffer is adopted in which deep donors are assumed to compensate deep acceptors, then the ionized deep donor usually plays a role as an electron trap. Calculated turn-on characteristics show that when impact ionization is not included, the drain current begins to increase relatively slowly because electrons are emitted from the deep donors, showing a large current collapse. On the other hand, when impact ionization is included and an ON-state drain voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {D} {{ \text {ON}}}}$ </tex-math></inline-formula> is high, generated holes between the gate and drain flow toward the buffer and are captured by neutral deep donors, particularly at the source side. The hole capturing time becomes relatively short when <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {D} {{ \text {ON}}}}$ </tex-math></inline-formula> is high and the hole density is high. Because of these increases in positive space charges in the buffer, the drain current increases relatively fast before the electron emission under the gate starts. Therefore, the current collapse becomes weaker when the impact ionization is considered and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {D} {{ \text {ON}}}}$ </tex-math></inline-formula> is higher. The situation may be similar with a different type of buffer such as an Fe-doped semi-insulating buffer in which the Fe-originated level (deep acceptor) is above the midgap and it usually plays a role as an electron trap.

Sensitive Assay for the Lactonase Activity of Serum Paraoxonase 1 (PON1) by Harnessing the Fluorescence Turn-On Characteristics of Bioorthogonally Synthesized and Geometrically Controlled Chemical Probes

The lactonase activity of paraoxonase 1 (PON1) has a crucial antiatherogenic function, and also serves as an important biochemical marker in human blood because the aberrant lactonase activity of PON1 is a key indicator for a number of diverse human diseases. However, no sensitive fluorescence assays that detect PON1 lactonase activity are available. We report the synthesis of two fluorescence turn-on chemical probes 16a and 16b (16) able to quantify PON1 lactonase activity. The chemical probes were constructed utilizing a disulfide-containing bicyclononyne, derivatives of rhodamine B and carboxyfluorescein, and reactions including copper-free azide–alkyne cycloaddition. Fluorescence quenching in 16 was characterized by spectroscopic studies and was mainly attributed to the effect of contact quenching. Kinetic analysis of 16b confirmed the outstanding reactivity and specificity of 16b with thiols in the presence of general base catalysts. The 16b-based assay was employed to determine PON1 lactonase activity, with a linear range of 10.8–232.1 U L−1 and detection limit (LOD) of 10.8 U L−1, to quantify serum PON1 activity in human sera, and to determine the Ki of 20.9 μM for the 2-hydroxyquinoline inhibition of PON1 lactonase. We are employing 16b to develop high-throughput assays for PON1 lactonase activity.

High-Performance Bidirectional Chemical Sensor Platform Using Double-Gate Ion-Sensitive Field-Effect Transistor with Microwave-Assisted Ni-Silicide Schottky-Barrier Source/Drain

This study proposes a bidirectional chemical sensor platform using ambipolar double-gate ion-sensitive field-effect transistors (ISFET) with microwave-assisted Ni-silicide Schottky-barrier (SB) source and drain (S/D) on a fully depleted silicon-on-insulator (FDSOI) substrate. The microwave-assisted Ni-silicide SB S/D offer bidirectional turn-on characteristics for both p- and n-type channel operations. The p- and n-type operations are characterized by high noise resistance as well as improved mobility and excellent drift performance, respectively. These features enable sensing regardless of the gate voltage polarity, thus contributing to the use of detection channels based on various target substances, such as cells, antigen-antibodies, DNA, and RNA. Additionally, the capacitive coupling effect existing between the top and bottom gates help achieve self-amplified pH sensitivity exceeding the Nernst limit of 59.14 mV/pH without any additional amplification circuitry. The ambipolar FET sensor performance was evaluated for bidirectional electrical characteristics, pH detection in the single-gate and double-gate modes, and reliability in continuous and repetitive operations. Considering the excellent characteristics confirmed through evaluation, the proposed ambipolar chemical sensor platform is expected to be applicable to various fields including biosensors. And through linkage with subsequent studies, various medical applications and precision detector operations for specific markers will be possible.

The Optimization of 3.3 kV 4H-SiC JBS Diodes

The article reports a comprehensive study optimizing the OFF- and ON-state characteristics of 3.3 kV junction barrier Schottky (JBS) diodes made using nickel, titanium, and molybdenum contact metals. In this design, the same implants used in the optimized termination region are used to form the P-regions in the JBS active area. The width and spacing of the P-regions are varied to optimize both the ON- and OFF-state of the device. All the diodes tested displayed high blocking voltages and ideal turn-on characteristics up to the rated current of 2 A. However, the leakage current and the Schottky barrier height (SBH) were found to scale with the ratio of Schottky to p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions. Full Schottkys, without p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions, and those with very wide Schottky regions had the lowest SBH (1.61 eV for Ni, 1.11 eV for Mo, and 0.87 eV for Ti) and the highest leakage. Those diodes with the lowest Schottky openings of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula> had the lowest OFF-state leakage, but they suffered severe pinching from the surrounding p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> regions, increasing their SBH. The best performing JBS diodes were Ni and Mo devices with the narrowest pitch, with the p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> implants/Schottky regions both <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 ~\mu \text{m}$ </tex-math></inline-formula> wide. These offered the best balanced device design, with excellent OFF-state performance, while the Schottky ratio guaranteed a relatively low forward voltage drop.