Amorphous carbon thin films

Silva, S.R.P.; Carey, J. D.; Khan, R. U. A.; Gerstner, Ed; Anguita, José V.

doi:10.1016/b978-012512908-4/50059-x

Cited by 30 publications

(39 citation statements)

References 321 publications

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“…In the 1990s, technological work on LAFEs dealt mainly with carbon-based materials [31,32]; however, the E&C interactions between an escaping electron and carbon-based emitters are not the same as for metals, and were not clearly understood in the 1990s. (It now seems [33] that for carbon nanotubes they may be weaker than the classical image PE.)…”

Section: More About Exchange-and-correlation Effectsmentioning

confidence: 99%

Extraction of emission parameters for large-area field emitters, using a technically complete Fowler–Nordheim-type equation

2012

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In papers on cold field electron emission from large area field emitters (LAFEs), it has become widespread practice to publish a misleading Fowler-Nordheim-type (FN-type) equation. This equation over-predicts the LAFE-average current density by a large highly-variable factor thought to usually lie between 10 3 and 10 9 . This equation, although often referenced to FN's 1928 paper, is a simplified equation used in undergraduate teaching, does not apply unmodified to LAFEs, and does not appear in the 1928 paper. Technological LAFE papers often do not cite any theoretical work more recent than 1928, and often do not comment on the discrepancy between theory and experiment. This usage has occurred widely, in several high-profile American and UK applied-science journals (including Nanotechnology), and in various other places. It does not inhibit practical LAFE development, but can give a misleading impression of potential LAFE performance to non-experts. This paper shows how the misleading equation can be replaced by a conceptually complete FN-type equation that uses three high-level correction factors. One of these, or a combination of two of them, may be useful as an additional measure of LAFE quality; this paper describes a method for estimating factor values using experimental data, and discusses when it can be used. Suggestions are made for improved engineering practice in reporting LAFE results. Some of these should help to prevent situations arising whereby an equation appearing in high-profile applied-science journals is used to support statements that an engineering regulatory body might deem to involve professional negligence.2

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Section: More About Exchange-and-correlation Effectsmentioning

confidence: 99%

Extraction of emission parameters for large-area field emitters, using a technically complete Fowler–Nordheim-type equation

2012

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“…Amorphous carbon ͑a-C͒ thin films have the added advantage that they can be deposited at low substrate temperatures where it is possible to achieve hard films with rms roughnesses of less than 1 nm over large areas. 1,2 This has led to applications such as hard disk and biomedical coatings. Less success has been forthcoming in the development of active electronic applications of a-C and hydrogenated a-C ͑a-C:H͒ films 3 and as a consequence it is necessary to examine the electronic properties and the effects of disorder and localization at a nanometer level.…”

Section: Introductionmentioning

confidence: 99%

Disorder, clustering, and localization effects in amorphous carbon

Carey

Silva

2004

Phys. Rev. B

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The nanostructure of amorphous carbon thin films is described in terms of a disordered nanometer-sized conductive sp 2 phase embedded in an electrically insulating sp 3 matrix. It is shown that the degree of clustering and disorder within the sp 2 phase plays a determining role in the electronic properties of these films. Clustering of the sp 2 phase is shown to be important in explaining several experimental results including the reduction of the electron spin resonance linewidth with increasing spin density and the dispersion associated with the width of the Raman active G band. The influence of structural disorder, associated with sp 2 clusters of similar size, and topological disorder, due to undistorted clusters of different sizes, on both spin density and Raman measurements, is discussed. An extension of this description to intercluster interactions to explain some of the electrical transport and electron field emission behavior is also presented.

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“…The presence of both sp 2 and sp 3 bonding results in a mixed phase material where many of the electronic, transport and optical properties are determined by the sp 2 phase with the mechanical and tribological properties being largely determined by the sp 3 phase [1,2]. The ability to deposit a-C films over large areas with mirror smooth surfaces has resulted in the use of these films in biomedical coatings and in hard disks, however, only limited success on the development of electronic devices has emerged [3].…”

Section: Introductionmentioning

confidence: 99%