Microscale surface potential gradient disturbances observed in bilayer graphene
Microscale surface potential gradient disturbances observed in bilayer graphene
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DOI：
10.1016/j.apsusc.2020.145504
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发表时间：
2020-04
影响因子：
6.7
通讯作者：
K. Gajewski;S. Ramadan;P. Kunicki;O. Shaforost;N. Klein;T. Gotszalk
中科院分区：
文献类型：
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作者：
K. Gajewski;S. Ramadan;P. Kunicki;O. Shaforost;N. Klein;T. Gotszalk
近年来，范德华单质和异质结构由于其新的物理和电子特性而受到广泛关注。人们根据其特性开发了几种新颖的器件结构，包括隧道晶体管、发光二极管和势垒电阻。然而，此类结构的构造通常涉及转移技术，这可能会引起损坏并改变结构的电子特性并降低器件性能。在这里，我们表明石墨烯的多步转移过程可能会扰乱其微观尺度的传输特性。使用 PMMA 作为支撑材料，将双层石墨烯转移到具有预先图案化的铬-钯电极的 Al2O3/Si 基板上。使用扫描隧道电位测量法，我们观察到局部电位梯度（以及产生的电流）与电极位置和偏置产生的电位梯度相比显着变化。这可能归因于局部材料广告层、未指定的接触或子层之间存在的添加剂。这一发现代表了理解转移技术对多层范德华单质和异质结构质量影响的重要一步。
Van der Waals mono- and heterostructures have received great attention in recent years due to their new physics and electronic properties. Several novel device structures have been developed based on their properties, including tunnelling transistors, light emitting diodes and barristors. However, the construction of such structures usually involves transfer techniques which could induce damage and modify the electronic properties of the structures and degrade device performance. Here we show that a multi-step transfer process for graphene may disturb its transport properties at microscale. Bilayer graphene was transferred, using PMMA as supporting material, onto an Al2O3/Si substrate with pre-patterned chromium-palladium electrodes. Using scanning tunnelling potentiometry, we observed that the local potential gradient (and resulting current flow) significantly changed compared with the potential gradient arising from the electrodes’ position and biasing. This could be attributed to local material ad-layers, unspecified contact or additives present between sub-layers. This finding represents an important step in understanding the effect of transfer techniques on the quality of multilayer van der Waals mono- and heterostructures.