Researchers at City University of Hong Kong have introduced a breakthrough approach in semiconductor technology using mixed-dimensional transistors. This innovation paves the way for more efficient, higher-performance electronics, overcoming the challenges of traditional dimensionality reduction techniques and highlighting a major leap toward advanced multifunctional integrated circuits.
The miniaturization of electronic components, including transistors, has reached a bottleneck that creates obstacles in semiconductor production. However, a team of researchers led by materials science experts at City University of Hong Kong (CityU) has introduced a new method to create multifunctional, high-performance electronic components using transistors made of hybrid dimensional nanowires and nanosheets. This breakthrough could help simplify chip circuit design and facilitate the development of future flexible and energy-efficient electronic devices.
As the expansion of transistors and integrated circuits has begun to reach physical and economic limits in recent decades, fabricating semiconductor devices in a controllable and cost-effective manner has become a challenge. Further expansion in transistor size increases leakage current and thus power dissipation. Complex cabling networks can also adversely affect power consumption.
Multi-valued logic (MVL) has emerged as a promising technology to overcome increasing power consumption. It transcends the limitations of traditional binary logic systems and greatly reduces the number of transistor components and their interconnections, thereby achieving higher information density and lower power consumption. Efforts have been made to construct various multivalued logic devices, including anti-bipolar transistors (AATs).
Breakthrough progress in anti-bipolar transistors
An anti-bipolar device is a type of transistor in which both positive (hole) and negative (electron) charge carriers can be transmitted simultaneously within the semiconductor channel. However, existing anti-bipolar devices mainly use two-dimensional or organic materials, which are not stable for large-scale semiconductor device integration. Furthermore, their frequency characteristics and energy efficiency are rarely explored.
In response to these limitations, a research team led by Professor Ho Chung-yin, Associate Vice-President (Enterprise) and Deputy Head of the Department of Materials Science and Engineering of City University of Hong Kong, set out to develop anti-bipolar device circuits with higher information density and fewer interconnections, and to explore their frequency characteristics.
The research team used advanced chemical vapor deposition technology to create a new type of mixed-dimensional heterotransistor that combines the unique properties of high-quality gallium arsenide antimony nanowires and MoS2 nanosheets.
Revolutionary mixed-dimensional transistor
New anti-bipolar transistor delivers outstanding performance. Since the mixed-dimensional GaAsSb/MoS2 junction has strong interface coupling and strip structure arrangement characteristics, this heterogeneous transistor has outstanding anti-bipolar transmission characteristics and can achieve transconductance flipping.
Compared to conventional frequency multipliers in CMOS technology, the flipping of transduction doubles the frequency response of the input analog circuit signal, significantly reducing the number of components required. Professor He said: "Our mixed-dimensional anti-bipolar transistor can realize multi-valued logic circuits and frequency multipliers at the same time, which is the first time in the field of anti-bipolar transistor applications."
The multi-valued logic feature simplifies complex wiring networks and reduces chip power consumption. Reduced device size and junction area make devices both fast and energy-efficient, enabling high-performance digital and analog circuits.
"Professor He said: "Our research results show that hybrid-dimensional anti-bipolar devices can achieve chip circuit design with high information storage density and information processing capabilities. To date, most researchers in the semiconductor industry have focused on device miniaturization to keep Moore's Law going. However, the emergence of anti-bipolar devices demonstrates the relative superiority of existing binary logic-based technologies. The technology developed in this research represents a major step toward the next generation of multifunctional integrated circuits and telecommunications technology. "
This research also provides the possibility to further simplify complex integrated circuit designs to improve performance.
The transconductance flipping capability of this mixed-dimensional anti-bipolar device shows broad applications in digital and analog signal processing, including ternary logic inverters, advanced optoelectronics, and frequency doubling circuits. Professor He added: "The new device structure heralds the potential for a future revolution in multifunctional electronics."
Compiled source: ScitechDaily