The diamond (111) surface: A dilemma resolved

Pate, Bradford B.; Waclawski, B; Stefan, P.M.; Binns, C.; Ohta, Tomohiro; Hecht, M. H.; Jupiter, P.J.; Shek, M. L.; Pierce, Daniel T.; Swanson, N.; Celotta, Robert; Lindau, I.; Spicer, W. E.; Rossi, Giovanni E.

doi:10.1016/0378-4363(83)90652-6

Cited by 27 publications

(15 citation statements)

References 14 publications

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“…The clean (2ϫ1) reconstructed as well as the oxygenated diamond ͑111͒ surfaces show PEA while the hydrogen-terminated (1ϫ1) surface exhibits NEA. 12,13,14 Considering the considerable number of publications concerned with one or the other aspect of the dehydrogenation process and the reconstruction of the diamond ͑111͒ surface one might ask, why another study? The present study differs from the previous ones in several important aspects.…”

Section: Introductionmentioning

confidence: 99%

Dehydrogenation and the surface phase transition on diamond (111): Kinetics and electronic structure

1999

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The (1ϫ1) to (2ϫ1) surface phase transition of the hydrogen-covered diamond ͑111͒ surface is investigated by core level spectroscopy, low-energy electron diffraction, and measurements of the electron affinity. The latter method is shown to be a reliable measure of the hydrogen coverage. Prolonged annealing of the surface at 1000 K converts the hydrogen-terminated (1ϫ1) structure with an electron affinity of Ϫ1.27 eV to a hydrogen-free (2ϫ1) reconstruction, increases the separation of valence-band maximum from the Fermi level E F from 0.68 to 0.88 eV, and results in a positive electron affinity of ϩ0.38 eV. Annealing the surface at high temperature ͑up to 1400 K͒ yields the same (2ϫ1) surface structure albeit with an increase in the separation of the valence-band maximum from E F to 1.42 eV and a positive electron affinity of 0.8 eV which is associated with a partial surface graphitization. An analysis of the kinetics of the thermally induced hydrogen desorption yields an activation energy of 1.25Ϯ0.2 eV. It was found that hydrogen desorption and reconstruction are surface phase transitions which are not directly linked. Instead, an intermediate phase with a high concentration of dangling bonds ͑up to 70%͒ is observed. The (1ϫ1) to (2ϫ1) phase transition is phenomenologically well described by a first-order transition provided a critical density of dangling bonds of about 70% is included in the analysis in such a way that the rate constant for reconstruction vanishes below that value. ͓S0163-1829͑99͒10407-7͔

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Section: Introductionmentioning

confidence: 99%

Dehydrogenation and the surface phase transition on diamond (111): Kinetics and electronic structure

1999

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“…6 Gas phase hydrogen atoms may also produce condensable carbon radicals by reactions with hydrocarbons, 7 and, impinging on the surface, they may create surface radicals [8][9][10] and refill vacant sites by adsorption. 8,11 Once adsorbed, atomic hydrogen may also stabilize the diamond surface structure. [12][13][14] The role of atomic hydrogen in diamond CVD has been studied from a theoretical point of view by several authors, including Frenklach et al, [15][16][17] Matsui et al, 18,19 Janssen et al, 12 Harris, 20,21 and Goodwin.…”

Section: Introductionmentioning

confidence: 99%

Spatial distributions of atomic hydrogen and C2 in an oxyacetylene flame in relation to diamond growth

Klein-Douwel

Meulen

1998

Journal of Applied Physics

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Two-dimensional laser induced fluorescence measurements are applied to the chemical vapour deposition of diamond by an oxyacetylene flame to visualize the distributions of atomic hydrogen and C 2 in the gas phase during diamond growth. Experiments are carried out in both laminar and turbulent flames and reveal that atomic hydrogen is ubiquitous at and beyond the flame front. Its presence extends to well outside the diamond deposition region, whereas the C 2 distribution is limited to the flame front and the acetylene feather. The diamond layers obtained are characterized by optical as well as scanning electron microscopy and Raman spectroscopy. Clear relations are observed between the local variations in growth rate and quality of the diamond layer and the distribution of H and C 2 in the boundary layer just above the substrate. These relations agree with theoretical models describing their importance in ͑flame͒ deposition processes of diamond. Three separate regions can be discerned in the flame and the diamond layer, where the gas phase and diamond growth are predominantly governed by the flame source gases, the ambient atmosphere, and the interaction of both, respectively.

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“…These surface states are dependent on the chemistry on the semiconductor surface. It has been found that hydrogen 24 and oxygen 25 terminated diamond surfaces do not exhibit significant surface states, Ͻ10 12 cm −2 , to pin the Fermi energy. It is not known whether the oxygen-caesium terminated diamond surface has significant surface states that may pin surface energy.…”

Section: Surface Emission Cathodesmentioning

confidence: 99%

A new surface electron-emission mechanism in diamond cathodes

Geis

Efremow

Krohn

et al. 1998

Nature

234

138

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An electron-emission mechanism for cold cathodes is described based on the enhancement of electric fields at metaldiamond-vacuum triple junctions. Unlike conventional mechanisms, in which electrons tunnel from a metal or semiconductor directly into vacuum, the electrons here tunnel from a metal into diamond surface states, where they are accelerated to energies sufficient to be ejected into vacuum. Diamond cathodes designed to optimize this mechanism exhibit some of the lowest operational voltages achieved so far.Conventional cathodes for applications from television to power transmitters use heat to boil electrons out of a metal into vacuum. However, these cathodes do not have the power efficiency or the dimensional stability to be used with micrometre-size structures, which are required for flat-panel displays and some power amplifiers. Cathodes that can be scaled to micrometre sizes use high electric fields instead of heat to pull electrons out of a solid into vacuum. The reliability and current density of these electric field emission cathodes depend upon both their geometry and the material used in their construction. Here we review field emission cathodes and show that a new cathode geometry which uses a novel material, diamond, has properties superior to those of previous cathodes.For the cold cathodes we discuss, emission is obtained with a large electric field that causes electrons to tunnel over a potential barrier out of a metal substrate into vacuum. Material and fabrication techniques have both been used to increase emission by enhancing the electric field and reducing the barrier over which the electrons must tunnel. Excellent low electric field electron emission has been reported from diamond and amorphous diamond-like films on metal substrates, but practical application of these cathodes is limited by a serious lack of reproducibility 1-3 and inconsistency (M. E. Kordesch, personal communications). Emission originates from a few localized sites, which were believed to be due to the inconsistent bulk properties of the cathode material. The enhanced emission at the interface between the diamond surface, a conductive region, and vacuum, a new emission mechanism, may explain the localization of emission sites. If so, a discontinuous diamond film that provides an abundance of interfaces should be a better electron emitter than a continuous diamond film 4,5 .We now describe two generally accepted emission mechanisms: geometric electric-field enhancement 6 , and Schottky diode with a negative-electron-affinity semiconductor 2,3 . Semiconductors and insulators have a negative electron affinity (NEA) if the minimum energy of electrons in the conduction band is above the minimum energy of electrons in vacuum. Experimental results are then described that cannot be explained by the previous emission mechanisms. A mechanism is proposed that combines the high electric fields that can be obtained at the intersection of a semiconductor surface, a metal substrate and vacuum (a so-called triple junction) 7,8 with t...

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The diamond (111) surface: A dilemma resolved

Cited by 27 publications

References 14 publications

Dehydrogenation and the surface phase transition on diamond (111): Kinetics and electronic structure

Dehydrogenation and the surface phase transition on diamond (111): Kinetics and electronic structure

Spatial distributions of atomic hydrogen and C2 in an oxyacetylene flame in relation to diamond growth

A new surface electron-emission mechanism in diamond cathodes

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