报告人：韩拯教授(山西大学)

时间：:2023年9月22日 (周五) 上午10:00

地点：清华-富士康纳米研究中心4楼报告厅

报告内容：Over the past half-century, exciton insulators have been observed in various experimental systems, predominantly through indirect spectroscopic studies. However, there is a notable lack of studies on the electrical transport and gate-tuning of this correlated insulator. The main reason for this limitation is the difficulty in controlling the strength of electron correlations in semi-metallic systems (or narrow bandgap semiconductors) near charge neutrality.

In this talk, we show that by bringing Bernal-stacked bilayer graphene (BLG) into contact with a few-layered insulator trOCl, the resulted vertical heterostructures can give rise to an extraordinarily robust ground state of insulator at the charge neutrality [1]. This emerged band-gap is of quantum origin, and can be controlled by in-plane electric fields, vertical electric fields, temperature, and carrier density.

Based on this correlated insulating state, both N-type and P-type transistors are achieved. Further cMOs-like semiconducting BLG logic inverter with a gain of approximately 1.2 (yet to be improved) at a temperature of 1.5 K at an input voltage of 0.2 V can be realized. This could be a crucial step forward for future carbon computing.

Unlike the conventional approaches based on intrinsic band gaps and doping principles in silicon-based semiconductors and two-dimensional semiconductors, the route of quantum-origin correlated gapped state employed in this study breaks new ground. lt constructs long-range charge order at the interface by utilizing interface coupling and then leverages the interface states to influence electronic correlations in graphene. This coupling mechanism represents a universal contro method and holds the potential for discovering intriguing physical phenomena in a broader range of two-dimensional electron systems [2].

References：

[1] K N Yang, X. Gao., Y. Wang,. T. Zhang, et al, Nat. Commun., 14, 2136 (2023).

[2] X. Lu, et al. Nat.Commun., 14, 5550（2023）.

报告人简介:山西大学韩拯教授在新原理低维量子器件等方面取得系列进展: 演示了本征二维磁性半导体自旋场效应管(Nat.Nanotechnol.，13，554，2018);发现了门电压可调的二维巨各向异性电阻效应(Nat. Nanotechnol., 10,2302,2019);制备的达到物理极限的单原子层亚纳米鳍片宽度FinFET 鳍栅晶体管(Nat.Commun.，11，1205，2020)入选《半导体学报》“中国半导体十大进展”;揭示了双重对齐莫尔超晶格中弱相互作用下的关联绝缘态(Nat.Commun., 12,7196,2021);发展了一种界面电荷序调控二维电子气关联效应的新方法，实现了极具鲁棒性量子霍尔态，液氮温度获得量子化边界导电态只需要0.35T磁场，为目前的世界记录(Nat.Nanotechno., 17,1272,2022)。韩拯教授先后入选国家级人才计划、国家级特殊人才支持计划;曾获“山西省五四青年奖章”、“山西省五一劳动奖章”、“MIT科技评论中国区35岁以下创新35人”等荣誉。