Zhang Zihao, Zhang Baoqing, Zhang Yifei, Wang Yiming, Hays Patrick, Tongay Seth Ariel, Wang Mingyang, Han Hecheng, Li Hu, Zhang Jiawei, Song Aimin
Institute of Nanoscience and Applications, Southern University of Science and Technology, Shenzhen, China.
Shandong Technology Center of Nanodevices and Integration, School of Integrated Circuits, Shandong University, Jinan, China.
Nat Commun. 2025 May 23;16(1):4805. doi: 10.1038/s41467-025-58720-7.
Negative differential resistance (NDR), a peculiar electrical property in which current decreases with increasing voltage, is highly desirable for multivalued logic gates, memory devices, and oscillators. Recently, 2D quantum-tunneling NDR devices have attracted considerable attention because of the inherent atomically flat and dangling-bond-free surfaces of 2D materials. However, the low current density of 2D NDR devices limits their operating frequency to less than 2 MHz. In this study, graphene/hexagonal boron nitride (h-BN)/graphene resonant tunneling transistors (RTTs) were fabricated using graphene and h-BN barriers with different numbers of atomic layers, showing a mechanism enabling the observation of NDR in high current density devices. A triangular etching approach was proposed to suppress the effects of graphene-metal contact resistance and graphene sheet resistance, enabling pronounced NDR effect even in a 2D tunneling device with a single atomic layer h-BN barrier. A room-temperature peak current density up to 2700 μA/μm and operational frequencies up to 11 GHz were achieved, demonstrating the potential of 2D quantum NDR devices for applications in high-speed electronics.
负微分电阻（NDR）是一种特殊的电学特性，即电流随电压升高而降低，对于多值逻辑门、存储器件和振荡器来说是非常理想的特性。最近，二维量子隧穿NDR器件因其二维材料固有的原子级平整且无悬空键的表面而备受关注。然而，二维NDR器件的低电流密度将其工作频率限制在2兆赫兹以下。在本研究中，使用具有不同原子层数的石墨烯和六方氮化硼（h-BN）势垒制造了石墨烯/六方氮化硼/石墨烯共振隧穿晶体管（RTT），展示了一种在高电流密度器件中实现NDR观测的机制。提出了一种三角形蚀刻方法来抑制石墨烯-金属接触电阻和石墨烯片电阻的影响，即使在具有单原子层h-BN势垒的二维隧穿器件中也能实现显著的NDR效应。实现了高达2700微安/微米的室温峰值电流密度和高达11吉赫兹的工作频率，证明了二维量子NDR器件在高速电子学应用中的潜力。
