Abstract
Two-dimensional (2D) molybdenum disulfide (MoS2) is the most mature material in 2D material fields owing to its relatively high mobility and scalability. Such noticeable properties enable it to realize practical electronic and optoelectronic applications. However, contact engineering for large-area MoS2 films has not yet been established, although contact property is directly associated to the device performance. Herein, we introduce graphene-interlayered Ti contacts (graphene/Ti) into large-area MoS2 device arrays using a wet-transfer method. We achieve MoS2 devices with superior electrical and photoelectrical properties using graphene/Ti contacts, with a field-effect mobility of 18.3 cm2/V∙s, on/off current ratio of 3 × 107, responsivity of 850 A/W, and detectivity of 2 × 1012 Jones. This outstanding performance is attributable to a reduction in the Schottky barrier height of the resultant devices, which arises from the decreased work function of graphene induced by the charge transfer from Ti. Our research offers a direction toward large-scale electronic and optoelectronic applications based on 2D materials.
Highlights
Two-dimensional (2D) molybdenum disulfide (MoS2 ) has emerged as a post-silicon material because of its outstanding electrical and optical properties compared with its bulk counterparts [1,2]
We developed graphene-interlayered Ti contacts to improve the device performance of large-area MoS2 films grown by chemical vapor deposition (CVD)
A thickness of 0.7 nm was measured by atomic force microscopy (AFM) analysis, which implies that our MoS2 film is a monolayer (Figure 1b,c) [18]
Summary
Two-dimensional (2D) molybdenum disulfide (MoS2 ) has emerged as a post-silicon material because of its outstanding electrical and optical properties compared with its bulk counterparts [1,2]. Its well-established scaled-up production and tunable bandgap depending on the number of layers make it promising for potential electronic and optoelectronic applications [1,2,3]. To realize electronic and optoelectronic devices based on MoS2 , suitable contact engineering is essential because the Schottky barrier height (SBH) formed between MoS2 and metal contacts is critical for determining the field-effect mobility of the resultant device [4]. Das et al used scandium contacts, an extremely low-work-function metal, to achieve an outstanding mobility (~700 cm2 /V·s) [4]. There was a significant difference between the experimental and theoretical SBHs extracted from the Schottky–Mott limit because the metal-induced Fermi level pinning effect prevents a shift in the Fermi level depending on the metal work function [7,8]
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