Origin of Surface Conductivity in Diamond

Maier, Florian; Riedel, Marc; Mantel, B.F.; Ristein, J.; Ley, L.

doi:10.1103/physrevlett.85.3472

Cited by 877 publications

(618 citation statements)

References 24 publications

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“…Maier et al [7] gave the first experimental evidence that chemisorbed hydrogen is a necessary but not a sufficient prerequisite for such surface conductivity and that the electron acceptors are provided by atmospheric adsorbates, leading to the so called "transfer surface doping" model. Oxygen can play an important role in this process but its influence is not fully understood [8].…”

Section: Introductionmentioning

confidence: 99%

The role of (sub)-surface oxygen on the surface electronic structure of hydrogen terminated (100) CVD diamond

Deferme¹,

Tanasa²,

Amir³

et al. 2006

Diamond and Related Materials

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In this work, scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) were applied to investigate the surface morphology and the surface electronic structure of plasma-treated (100)-oriented CVD diamond films. These films were hydrogenated using a conventional MWPE-CVD (microwave plasma enhanced chemical vapour deposition) reactor containing a H2 or a H2/O2 mixture. A comparison is made between (100)-oriented CVD diamond films hydrogenated with and without a small addition of oxygen (1%). X-ray Photoelectron Spectroscopy (XPS) and UV Photoelectron Spectroscopy (UPS) measurements point to the presence of O-atoms at the (sub)-surface of the diamond film. The measured conductivity is significantly different for the two processes of hydrogenation. Annealing experiments point out that the samples, which were terminated using the H2/O2 mixture are still conductive enough after annealing at 410 °C to enable STM experiments. Here, we discuss the mechanism for STM imaging of H2/O2 treated diamond films, associated with surface states induced by the oxygen incorporation.

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Section: Introductionmentioning

confidence: 99%

The role of (sub)-surface oxygen on the surface electronic structure of hydrogen terminated (100) CVD diamond

Deferme¹,

Tanasa²,

Amir³

et al. 2006

Diamond and Related Materials

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“…4͒. 11 On the other hand, there is no hole accumulation at the non-H-terminated surfaces ͑i.e., in the oxygen terminated regions͒. In the case of hydrogen-terminated diamond surfaces, none or very low pH sensitivity has been measured, which might indicate that the density of adsorbed counter-ions is mainly determined by the amount of accumulated holes.…”

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confidence: 99%

p H sensors based on hydrogenated diamond surfaces

Garrido

Härtl

Kuch

et al. 2005

Applied Physics Letters

110

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We report on the operation of ungated surface conductive diamond devices in electrolytic solutions. The effect of electrolyte pH on the channel conductivity is studied in detail. It is shown that fully hydrogen terminated diamond surfaces are not pH sensitive. However, a pronounced pH sensitivity arises after a mild surface oxidation by ozone. We propose that charged ions from the electrolyte adsorbed on the oxidized surface regions induce a lateral electrostatic modulation of the conductive hole accumulation layer on the surface. In contrast, charged ions are not expected to be adsorbed on the hydrogen terminated surface, either due to the screening induced by a dense layer of strongly adsorbed counter-ions or by the absence of the proper reactive surface groups. Therefore, the modulation of the surface conductivity is generated by the oxidized regions, which are described as microscopic chemical in-plane gates. The pH sensitivity mechanism proposed here differs qualitatively from the one used to explain the behavior of conventional ion sensitive field effect transistors, resulting in a pH sensitivity higher than the Nernstian limit.

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“…(mm size) molecular junctions obtained by covalent bonding of a nanometer-thick molecular monolayer to a semiconducting substrate, different sources of fluctuations with possible influence on transport properties have been reviewed. They include: (i) upper electrode non uniformity including formation of conducting filaments through the insulating layer; 17 (ii) non uniformity in OML thickness resulting from low coverage, poor organization, and variable tilt angle of the molecular layer; 19,35 (iii) spatial dependence of some induced density of states in the molecular layer band gap due to the strong covalent bonding with underlying metal or semiconductor; 20,27 (iv) fluctuation of flat-band voltage 24 due to spatial dependence of either top electrode work function (e.g., due to metal oxidation), or Si electron affinity (e.g., due to semiconductor oxidation), or else molecular dipole density; (v) non uniform oxidation of the bottom metal or semiconductor creating interface traps which can be detected by specific trap assisted tunneling signature in noise dynamics or in C-V characteristics; 21,28,[32][33][34] (vi) redox effects consisting in charge transfer 33,50 from the semiconductor to the adventitious water layer which is present on any surface at the ambient, with some preferential water physisorption being expected on oxidized hydrophilic regions.…”

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Barrier height distribution and dipolar relaxation in metal-insulator-semiconductor junctions with molecular insulator: Ageing effects

Fadjie-Djomkam

Ababou‐Girard

Godet

2012

Journal of Applied Physics

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To cite this version:Alain-Bruno Fadjie-Djomkam, Soraya Ababou-Girard, Christian Godet. Barrier height distribution and dipolar relaxation in metal-insulator-semiconductor junctions with molecular insulator: Ageing effects. Journal of Applied Physics, American Institute of Physics, 2012, 112, pp.113701-1-113701-11 Related ArticlesAtomic layer deposition of Al2O3 on GaSb using in situ hydrogen plasma exposure Appl. Phys. Lett. 101, 231601 (2012) Defect induced mobility enhancement: Gadolinium oxide (100) on Si(100) Appl. Phys. Lett. 101, 222903 (2012) Band alignment in Ge/GeOx/HfO2/TiO2 heterojunctions as measured by hard x-ray photoelectron spectroscopy Appl. Phys. Lett. 101, 222110 (2012) Electronic properties at the oxide interface with silicon and germanium through x-ray induced oxide charging Appl. Phys. Lett. 101, 211606 (2012) A computational study of graphene silicon contact J. Appl. Phys. 112, 104502 (2012) Additional information on J. Appl. Phys. Electrical transport through molecular monolayers being very sensitive to disorder effects, admittance and current density characteristics of Hg//C 12 H 25 -n Si junctions incorporating covalently bonded n-alkyl molecular layers, were investigated at low temperature (150-300 K), in the as-grafted state and after ageing at the ambient. This comparison reveals local oxidation effects both at the submicron scale in the effective barrier height distribution and at the molecular scale in the dipolar relaxation. In the bias range dominated by thermionic emission and modified by the tunnel barrier (TB) attenuation, expðÀb 0 d T Þ, where d T is the thickness of the molecular tunnel barrier and b 0 is the inverse attenuation length at zero applied bias, some excess current is attributed to a distribution of low barrier height patches.Complementary methods are used to analyze the current density J(V, T) characteristics of metal-insulator-semiconductor tunnel diodes. Assuming a Gaussian distribution of barrier heights centered at qU B provides an analytical expression of the effective barrier height, qU EFF ðTÞ ¼ qU B þ ðkTÞb 0 d T À ðqdUÞ 2 =2kT; this allows fitting of the distribution standard deviation dU and tunnel parameter ðb 0 d T Þ over a wide temperature range. In a more realistic modeling including the voltage dependence of barrier height and circular patch area, the so-called "pinch-off" effect is described by a distribution of parameter c ¼ 3ðD P R 2 P =4Þ 1=3 , which combines interface potential modulation and patch area variations. An arbitrary distribution of c values, fitted to low-temperature J(V) data, is equally well described by Gaussian or exponential functions. Ageing in air also increases the interface oxidation of Si substrate and affects the density of localized states near mid gap, which typically rises to the high 10 11 eV À1 cm À2 range, as compared with D S < 10 11 eV À1 cm À2 in the as-grafted state. The bias-independent relaxation observed near 1 kHz at low temperature may be attributed either to dipoles in the alkyl chain in...

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Origin of Surface Conductivity in Diamond

Cited by 877 publications

References 24 publications

The role of (sub)-surface oxygen on the surface electronic structure of hydrogen terminated (100) CVD diamond

The role of (sub)-surface oxygen on the surface electronic structure of hydrogen terminated (100) CVD diamond

p H sensors based on hydrogenated diamond surfaces

Barrier height distribution and dipolar relaxation in metal-insulator-semiconductor junctions with molecular insulator: Ageing effects

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