#mosfets

Novel carbon nanotube-based transistors reach THz frequencies

Carbon nanotubes (CNTs), cylindrical nanostructures made of carbon atoms arranged in a hexagonal lattice, have proved to be promising for the fabrication of various electronic devices. In fact, these structures exhibit outstanding electrical conductivity and mechanical strength, both of which are highly favorable for the development of transistors (i.e., the devices that control the flow of current in electronics). In recent years, several electronics engineers have started using CNTs to develop various electronics, including metal-oxide-semiconductor field-effect transistors (MOSFETs). MOSFETs are transistors that control the flow of current through a semiconducting channel utilizing an electric field applied to a gate electrode. Notably, when arrays of CNTs are used to develop MOSFETs, they can operate at radio frequencies (RF), the range of electromagnetic waves that support wireless communication. The resulting MOSFETs could thus be particularly advantageous for the advancement of wireless communication systems and technologies.

You flip the switch. The gate goes low. And yet—your IGBT laughs in your face. Current keeps flowing.

Sounds like science fiction? Nope. It’s latch-up, and it’s every power engineer’s nightmare.

🔥 The Hidden Enemy Inside

Inside each IGBT hides a parasitic thyristor. Under high collector current, it wakes up and locks on. Suddenly, your gate signal means nothing. Your circuit is hijacked.

Result? Overheating. EMI chaos. Sometimes, even that dreaded puff of smoke engineers know too well.

⚡ The Hero: Commutation Circuits

To fight back, we use commutation circuits—the unsung heroes of reliable power design.

Old-school: RC snubbers & bulky tricks.

Smarter way: Proper gate resistance, damping, optimized PCB layout.

Big picture: Without commutation, your IGBT is a ticking time bomb.

🚀 Why You Should Care

Whether you’re driving motors, building an inverter, or experimenting with SiC/GaN devices—commutation is what keeps your system alive. It’s not just design polish. It’s survival.

💬 Your Turn

Ever lost a circuit to latch-up? Did your IGBT go up in smoke, or did you manage to tame it? Reblog & drop your story 👇 Someone out there needs your hack.

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💥 Price Revolution! SiC MOSFETs Ignite Domestic Replacement Era 💥 Chinese IDM makers achieve historic breakthroughs: SiC MOSFET unit prices now undercut silicon-based IGBTs and super-junction MOSFETs at equivalent power ratings – a landmark "price inversion". Companies like BASiC Semiconductor slash module costs to 70% of imported solutions via 8-inch wafer mass production and vertical integration, boosting system efficiency by 15%. VBsemi amplifies this advantage with proprietary substrate-thinning and wafer-level testing, achieving 92% wafer utilization and 18% YoY cost reduction. Their SiC modules demonstrate 12% lower switching loss than global rivals in BYD’s 800V platform tests, fueling China’s transition from tech follower to cost leader. Projected 2025 SiC adoption: >30% in EVs, with rapid expansion in solar inverters and charging piles.

🚗 Automotive-Grade MOS Survival Thresholds: From AEC-Q101 to 800V Platforms 🚗 EV intelligence demands high-voltage/high-frequency solutions. Infineon’s OptiMOS™ 7 cuts RDS(on) by 25% and boosts switching speed by 20% using copper-clip packaging and 12-inch thin-wafer tech. BYD’s 2025 sourcing prioritizes diodes/transistors for power modules, while SemiDrive’s ASIL-D certified MCUs and GigaDevice’s GD32A503 secure major shares. VBsemi’s automotive MOS family, AEC-Q101 Grade 0 certified, features a tri-clad copper bonding structure reducing thermal resistance by 40%. Validated in XPENG’s brake-by-wire systems, it delivers millisecond response at -40°C with <10 PPM failure rates – setting new benchmarks for domestic reliability.

🌐 AI Compute Arms Race: DrMOS & Advanced Packaging Dual Fronts 🌐 NVIDIA’s GB300 NVL72 systems will drive 2025 DrMOS demand beyond 150M units, with AOS (70% share) as key supplier. NVIDIA’s cost-optimized 5x5mm DrMOS increases per-rack usage by 30% while halving unit prices, lifting server efficiency by 35%. TSMC’s CoWoS expansion and Chinese OSATs’ FOPLP/Chiplet projects push inter-chip bandwidth past 900GB/s. VBsemi’s next-gen DrMOS with Intelligent Phase Extension delivers 180A phase current in 5x5mm packages, accelerating dynamic response by 50%. Currently validating with Inspur, it boosts NVIDIA H100 GPU power efficiency by 0.8%, saving >$2,800/year per rack in electricity.

🌱 Circular Economy Reshapes Supply Chains: Recycling Boom to Lead-Free Wave 🌱 E-waste recycling surges in Shenzhen/Dongguan, with ICs fetching up to $23/PCS. EU’s 2026 lead-free mandate spurs demand for eco-components. VBsemi’s GreenMOS™ platform pioneers tin-whisker-resistant alloys and lead-free pre-plating, achieving 98% recyclability. Their super-junction MOS series passes IEC 61215 salt-mist certification, reducing coastal solar farm failures by 70%. BYD/CATL’s closed-loop systems target 85% material reuse by 2025.

🔋 Material Revolution: Silicon to Quantum Tunneling Breakthroughs 🔋 Third-gen semiconductors advance in parallel: TYSiC’s 8-inch SiC wavers hit 85% yield with 1.6% resistivity uniformity; Origin Quantum’s 72-qubit "Wukong" chip and IBM’s 1000-qubit processor mark quantum leaps. VBsemi’s hybrid gate-oxide tech (co-developed with CAS) slashes GaN HEMT gate leakage by 1,000x, enabling 97.2% efficiency at 2400V. Deployed in Huawei’s chargers, it achieves record 6.8W/cm³ power density.

💡 The Next Decade: From "China Replacement" to "Global Redefinition" 💡 Per BCG, 2025 global semiconductor market rebounds to $650B (AI chips +35%, consumer electronics +3%). China reconfigures supply chains via "wafer-fab origin" rules: SMIC’s 28nm capacity grows 5x in 3 years with 52% domestic equipment; JCET’s advanced packaging runs at >85% utilization. As Cambricon’s computing-in-memory chips rival global leaders and YMTC’s 128L NAND forces Samsung to cut prices by 15%, a multipolar tech era accelerates – with VBsemi’s innovations at its core.

👉 Follow #MOSElectronics #ChipRevolution #TechSovereignty for industry pulse!

Carbon nanotube–based MOSFETs doped using a scalable technique

In recent years, electronics engineers have been trying to identify materials that could help to shrink the size of transistors without compromising their performance and energy efficiency. Low-dimensional semiconductors, solid-state superconducting materials with fewer than three spatial dimensions, could help to achieve this. Among low-dimensional semiconducting materials that have been found to be particularly promising for reducing the length of gates inside transistors are one-dimensional (1D) carbon nanotubes. Nonetheless, most proposed strategies to dope these materials and control the polarity inside them are not compatible with existing large-scale electronics production methods.

Deep-depletion: A new concept for MOSFETs

An international team of researchers has created a proof of concept that uses the deep- depletion regime in bulk-boron-doped diamond MOSFETs to increase hole channel carrier mobility

Silicon has provided enormous benefits to the power electronics industry. But performance of silicon-based power electronics is nearing maximum capacity.

Enter wide bandgap (WBG) semiconductors. Seen as significantly more energy-efficient, they have emerged as leading contenders in developing field-effect transistors (FETs) for next-generation power electronics. Such FET technology would benefit everything from power-grid distribution of renewable-energy sources to car and train engines.

Diamond is largely recognized as the most ideal material in WBG development, owing to its superior physical properties, which allow devices to operate at much higher temperatures, voltages and frequencies, with reduced semiconductor losses.

A main challenge, however, in realizing the full potential of diamond in an important type of FET -- namely, metal-oxide-semiconductor field-effect transistors (MOSFETs) -- is the ability to increase the hole channel carrier mobility. This mobility, related to the ease with which current flows, is essential for the on-state current of MOSFETs.

Speed vs Voltage: MOSFET Explained

A MOSFET is a semiconductor device that uses voltage to control current flow. Its core principle involves adjusting the width of the conductive channel by altering the gate voltage, thereby regulating the drain current.

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Exceptionally low temperatures and large magnetic fields perpendicular to the electron system's plane cause two-dimensional electron systems to display the Quantum Hall Effect. Throughout a wide range of charge carrier densities or magnetic field strengths, the Hall resistance computed by dividing the Hall voltage by the applied current is unique and consistent.

This blog covers the quantum hall effect's definition, fundamental principles (Landau levels and disorder), topological origin, applications, experimental realisations, and fresh findings.

Definition of quantum hall effect

Klaus von Klitzing's 1980 QHE observation earned him the 1985 Nobel Prize in Physics. He found that the Hall resistance quantised a fundamental quantity by integers to produce accurate, consistent values. This first finding is called the Integer Quantum Hall Effect (IQHE). The discovery of plateau values for fractional integers led to the 1982 discovery of the Fractional Quantum Hall Effect (FQHE). Despite its complexity, the FQHE remains an open study topic. Existence depends on electron interactions.

Fundamentals: Landau Levels and Disorder

Understanding the IQHE starts with Landau levels. A strong magnetic field quantises electrons' circular paths into discrete energy levels in a two-dimensional electron system. The Landau levels' significant degeneracy allows many electron states to coexist at the same energy. These energy levels further split when an electron's spin aligns with a high magnetic field due to the Zeeman effect. Hall resistance plateaus are caused by material disorder or contaminants.

Disorder broadens the crisp Landau levels into energy bands. Electron states can be localised or expanded in these bands. Extended states can travel, whereas localised states are limited and do not contribute to the flow. When the Fermi energy, the highest energy level occupied by electrons, falls within a “mobility gap” between Landau levels and the Hall conductivity stays constant, creating plateaus, the material acts as an insulator in the longitudinal direction. Importantly, the condition does not affect these plateaus' exact values.

Topological Origin

The IQHE's stability and resistance to microscopic disorder and macroscopic system deformations strongly suggest a topological origin. Hall effect integers are topological quantum numbers. Berry's phase, a quantum system's geometric phase, is intimately related to Chern numbers. Due to this link, the material's fundamental features, which are dictated by its topological structure, influence its electrical properties.

Metrology the discipline of measuring has various QHE applications.

Electrical Resistance Standard: Due to its precision of more than one part in a billion, quantised Hall conductance has become the new practical standard for electrical resistance. This standard is based on the von Klitzing constant, named for its discoverer. In 1990, this constant was standardised for global resistance calibrations. The 2019 revision of the International System of Units (SI) specified the von Klitzing constant and other fundamental constants like Planck's constant and the elementary charge exactly.

The IQHE accurately and independently determines the fine-structure constant. The basic constant describes the strength of elementary particle electromagnetic interaction.

Experimental Results and Discoveries

When a two-dimensional electron system forms in a thin silicon-based MOSFET surface layer, the QHE was first observed. It has been widely studied in semiconductor materials like gallium arsenide heterostructures.

QHE has been observed in graphene and other materials recently. Graphene exhibits a half-integer quantum Hall effect. This half-integer behaviour is caused by graphene's relativistic-like energy dispersion and electron-hole degeneracy at Dirac locations. In contrast to semiconductor devices, graphene's QHE can occur at temperatures near to ambient temperature.

QHE in Bi2O2Se thin films is a novel and intriguing discovery. In thicker Bi2O2Se films, researchers detected only even-integer quantum Hall states at extremely high magnetic fields. Strange conduct is attributed to a “hidden Rashba effect”. Local violation of inversion symmetry in [Bi2O2]$^{2+}$ layers causes opposite spin polarisations to cancel each other out.