In a significant advancement for microelectronics, a research team at The Hong Kong Polytechnic University (PolyU) has engineered a novel tunnelling field-effect transistor (TFET) that overcomes the physical limits of conventional semiconductor technology. The breakthrough, published in the journal Science, offers a pathway to energy-efficient computing and next-generation AI chips.
Conventional transistors rely on thermionic emission, which requires a minimum gating voltage of 60 millivolts (mV). This is known as the 'Boltzmann limit,' making subthreshold swing (SS) values below 60 mV per decade at room temperature physically impossible. This constraint has long hindered progress in high-performance electronics, as reducing power consumption while increasing speed becomes increasingly difficult.
Led by Prof. Jianhua HAO, Head of the Department of Physics and Materials and Chair Professor of Materials Physics and Devices at PolyU, the research team adopted a quantum tunnelling approach to bypass this barrier. By using ultra-thin heterostructures of 2D bismuth and indium selenide, created via pulsed laser deposition, they transformed the normally semi-metallic bismuth into a semiconductor in its 2D form. This allows charge carriers to tunnel efficiently into indium selenide through quantum tunnelling.
The resulting TFET achieved SS values well below the 60 mV per decade limit, operating at room temperature on silicon substrates. It required a gate-voltage range of only 160 mV, far lower than the 800 mV typically needed. Moreover, the device delivered a high output current and an exceptionally high ON/OFF current ratio, which is crucial for driving multiple downstream logic gates and reducing circuit delay.
Prof. Hao stated, 'By adopting quantum tunnelling, our TFET breaks through this boundary, paving the way for ultra-low-power, high-performance integrated circuits essential for emerging AI chips and advanced semiconductor applications.'
The collaboration involved researchers from the National University of Singapore, The Hong Kong University of Science and Technology, Peking University, and the Singapore University of Technology and Design. This development could lead to more efficient electronics, with implications for artificial intelligence, data centres, and mobile devices, where power consumption is a critical factor.
The research addresses a long-standing challenge in TFETs by combining high output current with a high ON/OFF ratio, making the technology more viable for practical applications. As the demand for computing power continues to grow, such innovations are essential to sustain progress in the semiconductor industry.
