Large Work Function Modulation of Monolayer MoS2 by Ambient Gases

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• 作者：Si Young Lee ; Un Jeong Kim ; JaeGwan Chung ; Honggi Nam ; Hye Yun Jeong ; Gang Hee Han ; Hyun Kim ; Hye Min Oh ; Hyangsook Lee ; Hyochul Kim ; Young-Geun Roh ; Jineun Kim ; Sung Woo Hwang ; Yeonsang Park ; Young Hee Lee
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：June 28, 2016
• 年：2016
• 卷：10
• 期：6
• 页码：6100-6107
• 全文大小：474K
• 年卷期：0
• ISSN：1936-086X

文摘

Although two-dimensional monolayer transition-metal dichalcogenides reveal numerous unique features that are inaccessible in bulk materials, their intrinsic properties are often obscured by environmental effects. Among them, work function, which is the energy required to extract an electron from a material to vacuum, is one critical parameter in electronic/optoelectronic devices. Here, we report a large work function modulation in MoS₂ via ambient gases. The work function was measured by an in situ Kelvin probe technique and further confirmed by ultraviolet photoemission spectroscopy and theoretical calculations. A measured work function of 4.04 eV in vacuum was converted to 4.47 eV with O₂ exposure, which is comparable with a large variation in graphene. The homojunction diode by partially passivating a transistor reveals an ideal junction with an ideality factor of almost one and perfect electrical reversibility. The estimated depletion width obtained from photocurrent mapping was ∼200 nm, which is much narrower than bulk semiconductors.