The distribution of oxide species in the Cs∕O activation layer on InP(100) negative electron affinity photocathodes

Lee, Dong-Ick; Sun, Yun; Liu, Zhi; Sun, Shiyu; Peterson, Samuel; Pianetta, P.

doi:10.1063/1.2786885

Cited by 5 publications

(2 citation statements)

References 23 publications

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“…This large work function reduction is due to the strong surface dipole from the Cs/O coating, as has been found on many other substrate materials, including InP, 20 GaAs, 17,21 and Ga 1−x In x As, 22 with a very similar deposition technique. The estimated thickness of our Cs/O layer on graphene is 7 ± 3 Å, similar to previous studies (see Section 5 in Supporting Information), in which the chemical composition and atomic arrangement of the thin Cs/O layer have been carefully analyzed.…”

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confidence: 55%

“…To lower the work function of a material, one typical approach is to lower the vacuum level by surface engineering, particularly by depositing a very thin layer (about one monolayer) of alkali metal, such as Cs, Li, Sr, or Ba, − that are sometimes combined with a proper amount of oxygen. Among these approaches, Cs/O coated materials typically have the lowest work function between 1.1 and 1.4 eV. − The underlying mechanism for the work function reduction through the application of a thin layer of Cs/O has been extensively studied in the 1960s and 1970s, primarily driven by the development of negative electron affinity (NEA) photocathodes. ,− …”

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confidence: 99%

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Engineering Ultra-Low Work Function of Graphene

Yuan¹,

Chang²,

Bargatin

et al. 2015

Nano Lett.

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Low work function materials are critical for energy conversion and electron emission applications. Here, we demonstrate for the first time that an ultralow work function graphene is achieved by combining electrostatic gating with a Cs/O surface coating. A simple device is built from large-area monolayer graphene grown by chemical vapor deposition, transferred onto 20 nm HfO2 on Si, enabling high electric fields capacitive charge accumulation in the graphene. We first observed over 0.7 eV work function change due to electrostatic gating as measured by scanning Kelvin probe force microscopy and confirmed by conductivity measurements. The deposition of Cs/O further reduced the work function, as measured by photoemission in an ultrahigh vacuum environment, which reaches nearly 1 eV, the lowest reported to date for a conductive, nondiamond material.

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confidence: 55%