Application of wide-gap semiconductors to surface ionization: Work functions of AlN and SiC single crystals

Pelletier, J.; Gervais, D.; Pomot, C.

doi:10.1063/1.333156

Cited by 76 publications

(26 citation statements)

References 42 publications

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“…The simulation box is surrounded by a thermal bath, while Neumann boundary conditions are used for the surface. While emission of phonons into the vacuum may be neglected, electrons with energies above the work function of SiC 53 can escape the surface. To account for this electron emission, we remove electrons at the surface with sufficient energies.…”

Section: Discussionmentioning

confidence: 99%

Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation

et al. 2014

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The controlled creation of defects in silicon carbide represents a major challenge. A wellknown and efficient tool for defect creation in dielectric materials is the irradiation with swift (E kin Z500 keV/amu) heavy ions, which deposit a significant amount of their kinetic energy into the electronic system. However, in the case of silicon carbide, a significant defect creation by individual ions could hitherto not be achieved. Here we present experimental evidence that silicon carbide surfaces can be modified by individual swift heavy ions with an energy well below the proposed threshold if the irradiation takes place under oblique angles. Depending on the angle of incidence, these grooves can span several hundreds of nanometres. We show that our experimental data are fully compatible with the assumption that each ion induces the sublimation of silicon atoms along its trajectory, resulting in narrow graphitic grooves in the silicon carbide matrix.

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Section: Discussionmentioning

confidence: 99%

Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation

et al. 2014

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“…Adapted from [34]. (b) Overview of the on and threshold electric fields (E on and E thr , respectively) and maximum current density, J max , for various materials used for field emission to date, in order of dimensionality (1D, 2D and bulk) and increasing work function (Φ), including 1D nanowires -AlQ 3 [35,36], Si [37][38][39], MgO [40,41], AlN [42][43][44][45], CdS [46][47][48][49], W [50][51][52], ITO [53], CuPC [54,55], InGaN [56][57][58], CNTs [59][60][61][62][63] Cu [64][65][66], ZnO [67][68][69][70][71][72], GaN [73,74], ZnMgO [70,75], WO [76][77][78][79] ), MoO 2 [80]…”

Section: Field Emission Application Of Cntsmentioning

confidence: 99%

X-ray generation using carbon nanotubes

et al. 2015

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Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

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“…The work function for 6H-SiC has been reported to be 4.80Ϯ0.05 eV. 40 For the work function of TiC, experimental values between 3.8 and 4.1 have been reported while theoretical calculations gave 4.6 ͑Refs. 42͒ and 4.7 eV.…”

Section: B the Schottky Barriersmentioning

confidence: 99%

Electronic structure, Schottky barrier, and optical spectra of the SiC/TiC {111} interface

1997

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A first-principles total energy and electronic structure study of 3C-SiC/TiC ͕111͖ interfaces was carried out using the full-potential linear-muffin-tin orbital method. Three distinct plausible structural models were identified and investigated including the relaxation of the most important structural degrees of freedom. All three models considered have a threefold symmetry axis and have a mutual boundary layer of carbon. They were found to be stable with respect to small rigid body translations parallel to the interface which would destroy the threefold symmetry. One of the models (B) is a twinned version of the other (A) while the third model (C) differs from A by a rigid body translation parallel to the interface. The A and C models contain a common carbon sublattice in both the zinc blende structure of the SiC and rocksalt structure of the TiC. While in model A the Ti's are on top of the Si atoms nearest to interface, they are in a hollow site between the Si atoms in both the B and C models. Model A is found to be metastable with a significantly higher energy than B and C. This is explained in terms of the occurrence of compressed Ti-Si nearest neighbor distances in the ideal structure. The expansion of the latter disrupts the interfacial Ti-C bonding. Our calculations find very nearly equal energies for the relaxed B and C models. This indicates that the occurrence of twinned ͑untwinned͒ structures on flat ͑stepped͒ surfaces as has been observed by electron microscopy is probably not due to a thermodynamic preference but rather to kinetic factors such as step-flow growth. All three structures have interface states in the band gap of SiC which are localized within two lattice planes from the interface and which pin the Fermi level. The nonbonding character of these interface states leads to nearly equal Schottky barriers for all three models. The optical dielectric functions for our interface models were calculated and show signatures of these interface states which should be detectable in the infrared range because of their strong anisotropy with respect to the interface plane.

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Application of wide-gap semiconductors to surface ionization: Work functions of AlN and SiC single crystals

Cited by 76 publications

References 42 publications

Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation

Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation

X-ray generation using carbon nanotubes

Electronic structure, Schottky barrier, and optical spectra of the SiC/TiC {111} interface

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