Hyewon Du: The introduction of straightforward fabrication technique to improve device performance at graphene/2D semiconductor junction

posted 2 Aug 2017, 01:38 by info admin   [ updated 2 Aug 2017, 01:39 ]
Hyewon Du(1), Kunsik An(2), Taekwang Kim(1), Somyeong Shin(1), Seonyeong Kim(1), Minho Song(1), Changhee Lee(2) and Sunae Seo(1)

(1) Department of Physics, Sejong University, Seoul, 143-747, South Korea
(2) Department of Electrical and Computer Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826

Graphene as a contact metal can be integrated with two-dimensional semiconductor (2D-SC) through the van der Waals interaction without the breakage of covalent bonds. This undamaged contact provides an atomically sharp interface by hindering Fermi-level pinning. [1] The lower Schottky barrier height has been often reported in Molybdenum disulfide (MoS2), the most common n-type 2D-SC, with graphene than other conventional metals. [2] Unfortunately, the typical fabrication methods involved with lithography and etching process accompany undesired deterioration such as defects and various residues on graphene surface. It obstructs electron injection at graphene/SC junction and results in the degradation of device performance such as contact resistance and mobility.
Here, we introduced Oxidation Scanning Probe Lithography (o-SPL) [3] to integrate multilayer MoS2 transistor with graphene electrode. This technique reduces graphene damage and contamination by minimizing necessary process. With the analysis of AFM, Raman and electrical transport, we could confirm the improved device performance. 

[1] Yuan Liu, et al. “Van der Waals Heterostructures and Devices” Nat Rev Mater, 1, 16042 (2016)
[2] Yuan Liu, et al. “Toward Barrier Free Contact to Molybdenum Disulfide Using Graphene Electrodes” Nano Lett, 15 (5), 3030-3034 (2015)
[3] Satoru Masubuchi, et al. “Atomic Force Microscopy Based Tunable Local Anodic Oxidation of Graphene” Nano Lett, 11 (11), 4542-4546 (2011)

Hyewon Du is currently a PHD student at the department of Physics, Sejong University, Korea. Her research interests are mainly focused on the device fabrication and investigation of electrical characterization in graphene/2D semiconductor heterojunctions such as graphene/MoS2 and graphene/pentacene.