Beyond Silicon: China's Breakthrough with Bismuth Oxyselenide Transistors

Introduction

The semiconductor industry has long been dominated by silicon-based technologies, which have driven the exponential growth of computing power for decades. However, as we approach the physical limitations of silicon, researchers worldwide are exploring alternative materials to sustain the momentum of Moore's Law. In this context, a groundbreaking development from Peking University in China has garnered significant attention: the creation of a silicon-free transistor using bismuth oxyselenide (Bi₂O₂Se), a two-dimensional (2D) material. This innovation not only promises enhanced performance and energy efficiency but also positions China as a formidable player in the global semiconductor industry.

The Silicon Conundrum: Reaching Physical Limits

For over half a century, silicon has reigned supreme in semiconductor manufacturing. Its abundance, stable oxide, and suitable band gap made it the perfect material for transistors, the fundamental building blocks of modern electronics. However, as transistors continue to shrink—with leading manufacturers now producing chips with features as small as 3 nanometers—we approach the quantum mechanical limits of silicon. At these dimensions, quantum tunneling leads to electron leakage, increased power consumption, and thermal issues that degrade performance.

Industry leaders have employed various architectural innovations to extend silicon's viability, including FinFET (fin field-effect transistor) and more recently GAA (gate-all-around) transistors. Despite these advancements, the fundamental limitations of silicon remain, prompting the search for alternative materials that can provide a path forward beyond silicon's physical constraints.

The Science Behind Bismuth Oxyselenide Transistors

Bismuth oxyselenide is a layered 2D material that exhibits exceptional electronic properties, making it a promising candidate for next-generation transistors. Its high electron mobility, air stability, and suitable bandgap (~0.8 eV) enable faster electron movement and better control of electrical currents compared to traditional silicon. Researchers at Peking University have leveraged these properties to engineer a transistor that replaces silicon with bismuth oxyselenide, resulting in a device that operates 40% faster and consumes 10% less energy than leading silicon chips[^1].

Crystal Structure and Electronic Properties

The unique crystal structure of Bi₂O₂Se consists of alternating layers of [Bi₂O₂]²⁺ and Se²⁻, creating a natural quantum well that confines electrons within two-dimensional planes. This confinement enhances electron mobility while reducing scattering, leading to improved electrical performance. The material's electronic band structure features a direct bandgap of approximately 0.8 eV, which is ideal for electronic applications as it allows for efficient switching between conductive and non-conductive states.

Another remarkable property of Bi₂O₂Se is its superior carrier mobility—reaching up to 28,900 cm²/V·s at low temperatures—significantly higher than silicon's typical mobility of around 1,400 cm²/V·s. Even at room temperature, Bi₂O₂Se maintains impressive mobility values, translating to faster switching speeds and reduced signal delays in transistor operation.

Gate-All-Around Architecture

The transistor's design features a gate-all-around (GAA) architecture, where the gate electrode wraps around all sides of the channel. This configuration enhances electrostatic control over the channel, reducing short-channel effects and enabling further device scaling[^2]. The combination of bismuth oxyselenide's superior material properties and the GAA architecture contributes to the transistor's impressive performance metrics.

GAA designs represent the cutting edge of transistor architecture, offering several advantages over previous designs like FinFETs. By surrounding the channel material completely, GAA structures provide:

Improved electrostatic control, which reduces leakage currents
Better short-channel effect suppression, allowing for further miniaturization
Enhanced current drive capability for faster operation
More uniform electrical field distribution, leading to consistent performance

The Peking University team optimized this architecture specifically for Bi₂O₂Se, accounting for the material's unique electronic properties to maximize performance. Their design incorporates high-k dielectric materials for the gate insulator, further improving control over the channel without increasing gate leakage.

Fabrication Breakthroughs

Creating functional transistors with novel 2D materials presents significant fabrication challenges. The research team developed several innovative processes to overcome these hurdles:

Epitaxial Growth of High-Quality Bi₂O₂Se Films

The researchers pioneered a molecular beam epitaxy (MBE) technique to grow high-quality, large-area Bi₂O₂Se films with minimal defects. This method enables precise control over film thickness down to a few atomic layers, essential for achieving consistent transistor performance. The growth process occurs in ultra-high vacuum conditions at carefully controlled temperatures, resulting in crystalline films with exceptional uniformity.

Novel Contact Engineering

One of the persistent challenges in 2D material electronics is achieving low-resistance contacts between the semiconductor and metal electrodes. The team developed a specialized contact engineering approach using pre-patterned palladium electrodes treated with a surface functionalization process. This technique reduces contact resistance by more than an order of magnitude compared to conventional methods, significantly improving device performance.

Integration with Existing Manufacturing Techniques

Perhaps most importantly, the researchers designed their fabrication process to be compatible with established semiconductor manufacturing techniques. This compatibility potentially allows for easier adoption by industry, as it doesn't require a complete overhaul of existing fabrication facilities—a critical consideration for commercial viability.

Performance Metrics: A Leap Forward

The bismuth oxyselenide-based transistors have demonstrated impressive performance metrics:

Speed
: Up to 40% faster than top-tier silicon chips produced by leading companies like Intel.
Energy Efficiency
: Consumes approximately 10% less energy compared to current silicon-based chips.
Operating Frequency
: Demonstrated reliable operation at frequencies exceeding 3.5 GHz, indicating potential applications in high-performance computing and telecommunications.
Subthreshold Swing
: Achieves near-ideal subthreshold swing of 65 mV/decade at room temperature, approaching the theoretical limit and enabling more efficient switching.
On/Off Ratio
: Exceeds 10⁸, providing excellent differentiation between the transistor's on and off states, which is critical for digital logic applications.

These improvements are attributed to the material's superior electrical properties and the innovative transistor architecture. Particularly noteworthy is the device's performance stability over thousands of operating cycles, suggesting good reliability—a critical factor for commercial applications.

Implications for the Semiconductor Industry

This breakthrough has far-reaching implications:

Diversification of Materials

Introducing bismuth oxyselenide as a viable alternative to silicon could diversify the materials used in semiconductor manufacturing, reducing reliance on a single material and potentially mitigating supply chain risks[^3]. The semiconductor industry has historically been predominantly silicon-based, leaving it vulnerable to disruptions in silicon supply chains. Material diversification represents a strategic shift toward greater resilience.

Furthermore, bismuth oxyselenide's unique properties may enable specialized applications where silicon performs suboptimally. High-frequency electronics, ultra-low-power devices, and flexible electronics could particularly benefit from these new material properties.

Supply Chain Independence

Developing silicon-free chips may reduce reliance on traditional silicon supply chains, which are often dominated by a few key players, thereby enhancing national security and technological sovereignty. China specifically stands to gain significant strategic advantages by pioneering this technology, potentially reducing its dependence on foreign semiconductor technologies during a period of increased trade tensions.

The geopolitical dimensions of semiconductor technology have become increasingly evident in recent years, with advanced chip manufacturing capability now considered a matter of national security by many governments. Indigenous development of next-generation semiconductor materials aligns with China's "Made in China 2025" initiative, which aims to increase self-sufficiency in high-tech industries.

Innovation Acceleration

This advancement could spur further research into two-dimensional materials and their applications in electronics, potentially leading to the discovery of new materials with even better performance characteristics. The success of bismuth oxyselenide may catalyze exploration of other 2D materials with promising electronic properties, such as transition metal dichalcogenides (TMDs), hexagonal boron nitride (h-BN), and various Xenes (silicene, germanene, etc.).

This research momentum could accelerate the development of an entire ecosystem of 2D material-based devices, including sensors, photovoltaics, and quantum computing components, extending well beyond the initial application in transistors.

Market Potential and Economic Impact

The potential economic impact of this technology is substantial across multiple sectors:

Computing and Data Centers

With superior energy efficiency and performance, Bi₂O₂Se transistors could significantly impact the computing industry. Data centers, which currently consume approximately 1-2% of global electricity, stand to benefit enormously from the 10% energy reduction these chips offer. For a typical hyperscale data center consuming 50 megawatts of power, this translates to potential savings of 5 megawatts—equivalent to powering thousands of homes.

The 40% performance improvement could enable more powerful systems for artificial intelligence, scientific computing, and complex simulations without proportional increases in energy consumption, addressing a critical challenge in high-performance computing.

Mobile and Edge Computing

The energy efficiency advantages of bismuth oxyselenide transistors make them particularly attractive for mobile and edge computing applications, where battery life and thermal management are significant constraints. Smartphones, tablets, and IoT devices could potentially see substantial improvements in battery life while delivering enhanced processing capabilities.

Automotive and Industrial Electronics

As vehicles become increasingly computerized and autonomous driving systems more sophisticated, the demand for high-performance, energy-efficient semiconductors in the automotive sector continues to grow. Bismuth oxyselenide transistors could enable more advanced driver assistance systems and autonomous features while minimizing energy consumption, a crucial consideration for electric vehicles.

Challenges and Considerations

While promising, several challenges must be addressed:

Scalability

Transitioning from laboratory prototypes to mass production requires overcoming significant technical and manufacturing hurdles, including the development of reliable and cost-effective fabrication processes for bismuth oxyselenide-based devices. Current methods of producing high-quality Bi₂O₂Se films, such as molecular beam epitaxy, are excellent for research purposes but may be too slow and expensive for commercial production.

Researchers must develop alternative growth methods that maintain material quality while offering higher throughput and lower costs. Chemical vapor deposition (CVD) appears promising, with recent advances demonstrating the growth of uniform Bi₂O₂Se films over large areas, though quality improvements are still needed to match the performance of MBE-grown films.

Integration

Integrating new materials into existing manufacturing processes and ensuring compatibility with current technologies is complex, necessitating the redesign of fabrication equipment and workflows. The semiconductor industry represents a massive infrastructure investment developed specifically around silicon processing, and adapting or replacing this infrastructure for new materials presents both technical and economic challenges.

Questions about how bismuth oxyselenide devices will interface with existing silicon-based components remain. Will hybrid systems be necessary during a transition period? Can current chip packaging techniques accommodate the new material? These integration challenges require collaborative solutions involving material scientists, device engineers, and manufacturing specialists.

Reliability

Long-term reliability and performance consistency of bismuth oxyselenide transistors need thorough evaluation to ensure they meet the stringent requirements of commercial applications. Semiconductor technologies typically require failure rates measured in parts per billion for critical applications, and reaching such reliability standards requires extensive testing under various operating conditions, including temperature extremes, humidity, mechanical stress, and prolonged operation.

The Peking University team has conducted preliminary reliability testing showing promising results, but more comprehensive studies spanning thousands of hours under various stress conditions will be necessary before commercial adoption.

Raw Material Considerations

The availability and supply chain stability of bismuth and selenium will become increasingly important if this technology scales up. Both elements are less abundant than silicon, though neither is currently considered a critical resource. Bismuth is often produced as a byproduct of lead and copper mining, while selenium is primarily recovered during copper refining.

Geological surveys indicate sufficient known reserves for large-scale applications, but establishing reliable supply chains and potentially developing recycling processes would be prudent for long-term sustainability.

Global Impact and Strategic Significance

China's advancement in silicon-free transistor technology could reshape the global semiconductor landscape:

Technological Leadership

This breakthrough potentially positions China as a leader in next-generation semiconductor technologies, challenging the dominance of established players in the industry[^4]. As the semiconductor industry approaches the limits of silicon scaling, whoever masters the next generation of materials stands to gain significant technological advantages and market share.

The timing is particularly significant given the broader context of the global chip shortage and increasing recognition of semiconductors as strategically vital technologies. By pioneering practical applications of 2D materials in electronics, China demonstrates growing capabilities in fundamental research and development that could eventually translate to commercial leadership.

Economic Growth

Stimulating domestic industries and reducing dependence on foreign semiconductor technologies could foster economic growth and job creation within China. The semiconductor value chain encompasses materials suppliers, fabrication equipment manufacturers, chip designers, foundries, and assembly/testing operations—all representing high-value economic activities.

Developing a competitive advantage in next-generation semiconductor materials could allow China to capture more of this value chain domestically, creating high-skilled jobs and contributing significantly to GDP growth.

Geopolitical Influence

Enhancing China's strategic autonomy in critical technology sectors could have significant geopolitical implications. Semiconductors have become increasingly politicized, with export controls, investment restrictions, and technology transfer limitations emerging as tools of national policy. Developing indigenous alternatives to current semiconductor technologies potentially reduces vulnerability to such measures.

Beyond reducing vulnerabilities, leadership in advanced semiconductor technology could enhance China's position in setting global technology standards and increase its influence in international technology governance frameworks.

Future Research Directions

The Peking University breakthrough opens several promising avenues for further research:

Materials Engineering

While bismuth oxyselenide shows impressive properties, continued materials engineering could further enhance performance. Research into doping strategies, defect management, and interface engineering could yield additional improvements in mobility, stability, and other key parameters.

Exploration of heterostructures—combinations of different 2D materials in layers—represents another promising direction. For example, combining Bi₂O₂Se with other 2D materials like graphene or hexagonal boron nitride could create devices with customized properties tailored for specific applications.

Advanced Architectures

Beyond the current GAA design, researchers are exploring even more sophisticated transistor architectures that could better leverage the unique properties of 2D materials. Concepts like vertical transistors, tunneling field-effect transistors (TFETs), and negative capacitance field-effect transistors (NCFETs) all show promise when combined with 2D materials like bismuth oxyselenide.

Hybrid Integration

Rather than viewing silicon and bismuth oxyselenide as competing technologies, research into hybrid integration approaches could yield systems that capitalize on the strengths of both materials. Silicon could continue to serve as the foundation for certain components while bismuth oxyselenide handles performance-critical functions, creating complementary systems with superior overall capabilities.

Conclusion

The development of bismuth oxyselenide-based transistors represents a significant milestone in semiconductor technology. While challenges remain in scaling and integration, the potential benefits in performance, energy efficiency, and strategic autonomy make this a development worth close attention from industry stakeholders worldwide.

As Moore's Law faces increasing physical and economic barriers, innovations in materials science like the Bi₂O₂Se transistor may provide the path forward for continued advancement in computing performance[^5]. This breakthrough from Peking University demonstrates that the future of semiconductors may not be limited to incremental improvements in silicon technology but could involve diverse materials with novel properties that overcome current limitations.

The race to develop practical, scalable alternatives to silicon is intensifying globally, with potentially far-reaching consequences for computing capabilities, economic competitiveness, and technological sovereignty. Whether bismuth oxyselenide ultimately becomes the successor to silicon or serves as one of many specialized materials in next-generation computing remains to be seen, but its emergence highlights the pivotal role of materials science in shaping the future of information technology.

References

[^1]: Tom's Hardware. (2025, March 12). "Chinese university designed 'world's first silicon-free 2D GAAFET transistor,' claims new bismuth-based tech is both the fastest and lowest-power transistor yet." Retrieved from https://www.tomshardware.com/pc-components/cpus/chinese-university-designed-worlds-first-silicon-free-2d-gaafet-transistor-new-bismuth-based-tech-is-both-the-fastest-and-lowest-power-transistor-yet

[^2]: Live Science. (2025, March 24). "China's new 2D transistor could soon be used to make the world's fastest processors." Retrieved from https://www.livescience.com/technology/electronics/chinas-new-2d-transistor-could-1-day-be-used-to-make-the-worlds-fastest-processors

[^3]: HotHardware. (2025, March 13). "New Breakthrough Transistor Tech Claims To Leave TSMC And Intel In The Dust." Retrieved from https://hothardware.com/news/chinese-bismuth-gaafet-breakthrough

[^4]: DNYUZ. (2025, May 3). "This Chinese breakthrough could change microprocessors forever." Retrieved from https://dnyuz.com/2025/05/03/this-chinese-breakthrough-could-change-microprocessors-forever/

[^5]: ACS Nano. "The Discovery of a High-Mobility Two-Dimensional Bismuth Oxyselenide Semiconductor and Its Application in Nonvolatile Neuromorphic Devices." Retrieved from https://pubs.acs.org/doi/10.1021/acsnano.3c02263

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