Beyond Moore’s Law: Revolutionary Hot Carrier Transistors Overcome Efficiency Challenges

By Chinese Academy of Sciences September 15, 2024

Collected at: https://scitechdaily.com/beyond-moores-law-revolutionary-hot-carrier-transistors-overcome-efficiency-challenges/

Researchers have developed a novel graphene-germanium hot-emitter transistor using a new hot carrier generation mechanism, achieving unprecedented performance. This advancement opens new possibilities for low-power, high-performance multifunctional devices.

Transistors, the fundamental components of integrated circuits, encounter increasing difficulties as their size continues to shrink. To boost circuit performance, it has become essential to develop transistors that operate on innovative principles. Hot carrier transistors, which harness the extra kinetic energy of charge carriers, offer the potential to enhance transistor speed and functionality. However, their effectiveness has been constrained by conventional methods of generating hot carriers.

A team of researchers led by Prof. Chi Liu, Prof. Dongming Sun, and Prof. Huiming Cheng from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences has proposed a novel hot carrier generation mechanism called “stimulated emission of heated carriers (SEHC).” The team has also developed an innovative hot-emitter transistor (HOET), achieving an ultralow sub-threshold swing of less than 1 mV/dec and a peak-to-valley current ratio exceeding 100. The study provides a prototype of a low-power, multifunctional device for the post-Moore era.

This work was published in Nature.

Role of Low-Dimensional Materials

Low-dimensional materials like graphene, due to their atomic thickness, excellent electrical and optical properties, and perfect surface without defects, can easily form hetero-structures with other materials. This creates a variety of energy band combinations, offering new possibilities for developing novel hot carrier transistors.

Researchers at IMR developed a hot-emitter transistor using a combination of graphene and germanium, leading to an innovative mechanism for hot carrier generation. This new transistor is composed of two coupled graphene/germanium Schottky junctions.

During operation, germanium injects high-energy carriers into the graphene base, which then diffuse to the emitter, triggering a substantial current increase due to the preheated carriers there. This design’s sub-threshold swing of less than 1 mV/dec surpasses the conventional “Boltzmann limit” of 60 mV/dec. Meanwhile, this transistor also shows a peak-to-valley current ratio exceeding 100 at room temperature. The potential for multi-valued logic computing has further been demonstrated based on these characteristics.

“This work opens a new realm in transistor research, adding a valuable member to the family of hot carrier transistors and showing broad prospects for their application in future high-performance, low-power, multifunctional devices,” said Liu.

Reference: “A hot-emitter transistor based on stimulated emission of heated carriers” by Chi Liu, Xin-Zhe Wang, Cong Shen, Lai-Peng Ma, Xu-Qi Yang, Yue Kong, Wei Ma, Yan Liang, Shun Feng, Xiao-Yue Wang, Yu-Ning Wei, Xi Zhu, Bo Li, Chang-Ze Li, Shi-Chao Dong, Li-Ning Zhang, Wen-Cai Ren, Dong-Ming Sun and Hui-Ming Cheng, 14 August 2024, Nature.
DOI: 10.1038/s41586-024-07785-3

This study was conducted in collaboration with Ren Wencai’s team from IMR and Zhang Lining’s team from Peking University.