清華大學材料科學與工程研究院《材料科學論壇》學術報告

報告時間：2023年9月22日上午10:00

報告人：韓拯教授（山西大學）

報告地點：清華—富士康納米中心四樓報告廳

邀請人：劉锴老師

報告題目：基于長程電荷序量子效應的新原理半導體器件探索

報告簡介：

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 CrOCl, 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. It 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 control method and holds the potential for discovering intriguing physical phenomena in a broader range of two-dimensional electron systems [2].

[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).

報告人簡介：

山西大學韓拯教授在新原理低維量子器件等方面取得系列進展：演示了本征二維磁性半導體自旋場效應管（Nat. Nanotechnol., 13, 554, 2018）；發現了門電壓可調的二維巨各向異性電阻效應（Nat. Nanotechnol., 10, 2302, 2019）；制備的達到物理極限的單原子層亞納米鳍片寬度FinFET 鳍栅晶體管（Nat. Commun., 11, 1205, 2020）入選《半導體學報》“中國半導體十大進展”；揭示了雙重對齊莫爾超晶格中弱相互作用下的關聯絕緣态（Nat. Commun., 12, 7196, 2021）；發展了一種界面電荷序調控二維電子氣關聯效應的新方法，實現了極具魯棒性量子霍爾态，液氮溫度獲得量子化邊界導電态隻需要0.35 T磁場，為目前的世界記錄（Nat. Nanotechnol., 17, 1272, 2022）。韓拯教授先後入選國家級海外青年人才計劃、國家級特殊人才支持計劃；曾獲“山西省五四青年獎章”、“山西省五一勞動獎章”、“MIT科技評論中國區35歲以下創新35人”等榮譽。