Science and Technology on Integrated Logistics Support Laboratory, National University of Defense Technology, Changsha, 410073, People's Republic of China. Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, FI-02150, Finland.
Nanotechnology. 2019 Jun 21;30(25):25LT01. doi: 10.1088/1361-6528/ab0d30. Epub 2019 Mar 6.
We demonstrate a fabrication scheme for clean suspended structures using chemical-vapor-deposition-grown graphene and a dry transfer method on lift-off-resist-coated substrates to facilitate suspended graphene nanoelectronic devices for technological applications. It encompasses the demands for scalable fabrication as well as for ultra-fast response due to weak coupling to environment. The fabricated devices exhibited initially a weak field-effect response with substantial positive (p) doping which transformed into weak negative (n) doping upon current annealing at the temperature of 4 K. With increased annealing current, n-doping gradually decreased while the Dirac peak position approached zero in gate voltage. An ultra-low residual charge density of 9 × 10 cm and a mobility of 1.9 × 10 cm V s were observed. Our samples display clear Fabry-Pérot (FP) conductance oscillation which indicates ballistic electron transport. The spacings of the FP oscillations are found to depend on the charge density in a manner that agrees with theoretical modeling based on Klein tunneling of Dirac particles. The ultra-low residual charge, the FP oscillations with density dependent period, and the high mobility prove the excellent quality of our suspended graphene devices. Owing to its simplicity, scalability and robustness, this fabrication scheme enhances possibilities for production of suspended, high-quality, two-dimensional-material structures for novel electronic applications.
我们展示了一种使用化学气相沉积生长的石墨烯和剥离-转移技术在光刻胶上制造清洁悬空结构的方案，以方便悬空石墨烯纳米电子器件的技术应用。它满足了可扩展制造以及由于与环境弱耦合而需要超快速响应的需求。所制造的器件最初表现出微弱的场效应响应，具有显著的正（p）掺杂，在 4 K 的电流退火温度下转变为微弱的负（n）掺杂。随着退火电流的增加，n 掺杂逐渐减少，而在栅电压下的狄拉克峰位置接近零。观察到超低的残余电荷密度为 9×10 cm 和迁移率为 1.9×10 cm V s。我们的样品显示出明显的法布里-珀罗（FP）电导振荡，表明弹道电子输运。FP 振荡的间隔被发现与电荷密度有关，这与基于狄拉克粒子的 Klein 隧穿的理论模型一致。超低的残余电荷、与密度相关的 FP 周期以及高迁移率证明了我们悬空石墨烯器件的优异质量。由于其简单、可扩展和稳健性，这种制造方案增强了生产新型电子应用的悬空、高质量二维材料结构的可能性。
