Water-Induced Negative Electron Affinity on Diamond (100)

Gao, Xingyu; Liu, Lei; Qi, Dongchen; Chen, Shi; Wee, Andrew Thye Shen; Ouyang, Ti; Yu, Xiaojiang; Moser, H. O.

doi:10.1021/jp0726337

Cited by 35 publications

(27 citation statements)

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“…We used the previous work of Reinke et al [33] and Gao et al [34] to interpret the spectra. Two distinct peaks are observed which we have labeled A and B (observed at 531.9 eV and 538.0 eV).…”

Section: Nexafs O(1s)mentioning

confidence: 99%

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

et al. 2014

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We report C(1s) and O(1s) surface sensitive x-ray photoelectron spectroscopy (XPS) and C and O K-edge partial-electron yield near-edge x-ray absorption fine structure (NEXAFS) measurements for (100) and (110) oxidized diamond surfaces, etched by a laser two-photon ultraviolet (UV) desorption process. Etched regions of the (100) surface show increased oxygen coverage with a higher fraction of singly bonded termination species than unetched regions. Similar changes are observed for the (110) but with smaller magnitude. For both surfaces, no major change in sp 2 bonded carbon is observed. We show that the terminations observed for etched surfaces are consistent with the formation of oxidized {111} facets. For deeply etched samples, atomic force microscopy and scanning electron microscopy confirm the presence of {111}-like facets and reveals the development of nanoscale facetted ridges directed perpendicular to the etching beam polarization. An etching mechanism is proposed involving localized optical absorption by surface electronic states, with the probability for subsequent desorption events varying according to the relative directions of laser polarization and lattice orientation.

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Section: Nexafs O(1s)mentioning

confidence: 99%

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

et al. 2014

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“…Annealing in air at 150 o C-300 o C led to a decrease in conductivity, which increased to the previous level after the sample was kept a few hours under normal conditions. Such behavior is quite expected for diamond films, in which a dipole layer formed by the ensemble of hydroxyl and hydride groups on the diamond surface is responsible for the high surface conductivity [8] and the negative electron affinity [49].…”

mentioning

confidence: 87%

Optical spectroscopy of the surface of nanoporous diamond films

et al. 2011

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We have studied the IR absorption spectra of samples of porous ultrananocrystalline diamond (UNC diamond) obtained by selective etching of the sp 2 phase in UNC diamond films. We show that the surface of porous UNC diamond is polyfunctional. We have studied the behavior of surface hydride, carbonyl, carboxyl, and hydroxyl groups as a function of annealing temperature in air and the time kept under normal conditions for UNC diamond films previously oxidized at 430 o C-450 o C. In the range from a few minutes to a few months, we studied the kinetics for establishment of the steady state for the functional adsorbed layer on the diamond surface under normal conditions. The observed growth in the intensity of the transmission bands due to hydride (CH x ) and other hydrogen-containing functional groups is explained by dissociation of water molecules on the surface of the UNC diamond films.Introduction. Diamond, a material with unique properties, has record high atomic density, thermal conductivity, speed of sound, and hardness, is optically transparent from the ultraviolet to the far IR range, and can operate under extreme conditions: at high temperatures and high radiation levels, in aggressive media [1]. Today it has become possible to obtain polycrystalline diamond by chemical vapor-phase deposition (CVD) in the form of plates of area equal to tens of square centimeters and thickness ranging from fractions of a micron to several millimeters. CVD diamond films (DFs) have been used as the basis to demonstrate prototypes for heat sinks, optical windows, x-ray apertures, ionizing radiation detectors, diodes, and other elements and devices [2]. The surface of diamond exhibits a broad range of electrochemical potential [3], can have negative electron affinity [4], and its coverage and accordingly its properties can be controlled. After treatment in a hydrogen plasma, the diamond surface becomes conducting (p type conductivity), and after oxidation it becomes insulating [5]. Based on the two-dimensional conductivity effect on the hydrogenated diamond surface, a new microwave field-effect transistor was fabricated with frequency f max up to 120 GHz [6]. Hydrogenation of the diamond surface is a necessary but not a sufficient condition for realization of high surface conductivity, which is apparent only when the diamond is in contact with the surrounding atmosphere [7], and the humidity of the air has a nonmonotonic effect on the surface conductivity of diamond [8]. In photochemical processes, a hydrogenated hydrophobic [9] diamond surface can add biomolecules via covalent bonds, while an oxidized hydrophilic diamond surface promotes molecular attraction and cell growth [10], where diamond is biocompatible and has low cytotoxicity [11]. Nanocrystalline CVD diamond films, owing to their smooth surface, their suitability for industrial production, their low cost when deposited on a substrate of large surface area and their compatibility with the electronic interface in devices with a planar configuration, are optimal materia...

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“…This latter has based on the singular surface property of the hydrogenated diamond. The negative electron affinity of the H-terminated diamond [77] induces redox reactions between diamond surface and adsorbates. It involves a shift of the valence band edge above the electrons Fermi level in diamond providing electron acceptor levels [78].…”

Section: Field Effect Transistorsmentioning

confidence: 99%

Diamond Biosensors

Hébert¹,

Ruffinatto²,

Bergonzo³

2014

Carbon for Sensing Devices

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Diamond is wide band gap semiconductor presenting many extreme properties. It is notably known as the most stable material with the highest chemical inertness, the highest mechanical hardness and the highest thermal conductivity [1-3]. Since the mid 1970s it has been possible to grow synthetic diamond by several methods. High Pressure High Temperature techniques that mimic the diamond formation in the earth's crust were first developed [4-6]. Then Chemical Vapour Deposition (CVD) methods enable diamond growth at laboratory scale [7-9] as well as the control the P-type and Ntype doping of diamond [10-13]. Besides, it is possible to tune the diamond electrical properties form very resistive to metallic thanks to the P-type doping with boron [14]. Current achievements have enabled the development of diamond sensors that can operate in extreme conditions [15-17]. After being used for its mechanical and thermal properties, diamond was considered for chemical sensing. In fact the chemical stability and the close-to-metallic conductivity of diamond make it a powerful tool for electrochemical detection in various environment. Furthermore, the diamond is an ideal substrate for surface functionalization thanks to the wide and very known carbon based chemistry. Such a feature combined to the outstanding electrochemical properties of the diamond electrodes have enable the production of very efficient biosensors and biochips. Diamond is also an interesting sensor for medical imaging. Its carbon nature, well tolerated by living tissues, are actually very useful for its use as a biosensor capable of working in contact with bio-environments as well as real neuronal interfaces. Both those topics will be discussed in details in the following pages. In a first part an overview on electrochemical based biosensors and their performance is described. Then in a second half of the chapter, novel applications where diamond is directly used as an electrode for neural tissue interfacing is presented in details.

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Water-Induced Negative Electron Affinity on Diamond (100)

Cited by 35 publications

References 50 publications

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

Nanostructuring and oxidation of diamond by two-photon ultraviolet surface excitation: An XPS and NEXAFS study

Optical spectroscopy of the surface of nanoporous diamond films

Diamond Biosensors

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