Impact of gas adsorption on the stability and electronic properties of negative electron affinity GaAs nanowire photocathodes

ABSTRACTWe have investigated, using density functional simulations, the energetics and the electronic properties of oxides of selected transition metals, TMs, adsorbed onto a dia-mond (001) surface. We find that stoichiometric oxides of TMs, particularly Ti and Zn,influence the electron affinity of diamond strongly. The electron affinities of stoichiomet-ric oxides of Ti and Zn are calculated to be around −3 eV, significantly higher than 1.9 eV of commonly used H–termination. The reactions of TMs with an oxygenated diamond are found to be highly exothermic. Based upon the energetics and the electronic properties, we propose that in the regime of ultra thin films, oxides of TMs are promising options for surface coating of diamond–based electron emitters, as these coatings are compatible with semiconductor device fabrication processes, while having the benefit of inducing a large negative electron affinity.

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Evolution of electronic properties at the p‐GaAs(Cs,O) surface during negative electron affinity state formation

Applied Physics Letters ◽

10.1063/1.113923 ◽

1995 ◽

Vol 66 (16) ◽

pp. 2122-2124 ◽

Cited By ~ 24

Author(s):

V. L. Alperovich ◽

A. G. Paulish ◽

H. E. Scheibler ◽

A. S. Terekhov

Keyword(s):

Electronic Properties ◽

State Formation ◽

Electron Affinity ◽

Negative Electron Affinity

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Structural and Electronic Properties of Negative Electron Affinity Epitaxial Diamond (110) Films Studied Using Atomic Resolution UHV STM

MRS Proceedings ◽

10.1557/proc-509-165 ◽

1998 ◽

Vol 509 ◽

Author(s):

S.C. Lim ◽

R.E. Stallcup ◽

I. Akwani ◽

J.M. Perez

Keyword(s):

Electronic Properties ◽

Electron Affinity ◽

Epitaxial Films ◽

Atomic Resolution ◽

Scanning Tunneling ◽

Negative Electron Affinity ◽

Tunneling Microscopy ◽

Structural And Electronic Properties ◽

Theoretical Predictions ◽

Photoelectric Threshold

AbstractWe report ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) studies of the structural and electronic properties of epitaxial diamond (110) films. We observe that epitaxial diamond (110) films grow very rough due to striations. The striations are found to be due to the appearance of(111) faces and contain (100) steps. UHV STM atomic resolution images of the diamond (110) films show a (lxi) zigzag structure that measures 1.5 ± 0.1 Å × 1.5 ± 0.1 Å, in agreement with theoretical predictions for the hydrogen terminated diamond (110) surface. Ultraviolet spectroscopy shows that the epitaxial films have a photoelectric threshold of 5.3 ± 0.1 eV, providing evidence that the films have a negative electron affinity surface.

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