n
          -type conductivity in ultrananocrystalline diamond films

Williams, Oliver A.; Curat, Stephane; Gerbi, J. E.; Gruen, D. M.; Jackman, Richard B.

doi:10.1063/1.1785288

Cited by 154 publications

(96 citation statements)

References 17 publications

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“…As derived from SIMS measurements, the boron concentration in the NCD films varies from 9.7x10 16 cm -3 in the non-intentionally doped (n.i.d.) film up to 3.3x10 21 cm -3 in the heavily boron doped NCD film ( Table I).…”

Section: A Structural Propertiesmentioning

confidence: 99%

“…32 In UNCD films the conductivity has been attributed to the presence of sp 2 carbon in the grain boundaries which increases with the amount of nitrogen in the gas phase. 15,16 Thus, it has been shown that electron transport occurs in a defect band at the grain boundaries. In contrast, our Hall effect experiments confirm that in the B-doped NCD films the conductivity is due to holes and not electrons, suggesting that electronic transport in the grain boundaries is not an important transport mechanism in B-doped NCD.…”

Section: B1 High Temperature Regimementioning

confidence: 99%

“…14 So far, the n-type conductivity induced by nitrogen addition during UNCD growth has been investigated in detail. 15,16 The p-type doping of diamond with boron has been extensively examined in single crystal (SCD) homoepitaxially grown material, 17,18,19,20 as well as in polycrystalline materials (PCD). 21,22 In the case of heavily boron doped samples, superconductivity has been reported.…”

Section: Introductionmentioning

confidence: 99%

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Electronic and optical properties of boron-doped nanocrystalline diamond films

et al. 2009

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We report on the electronic and optical properties of boron-doped nanocrystalline diamond (NCD) thin films grown on quartz substrates by CH 4 /H 2 plasma chemical vapor deposition.Diamond thin films with a thickness below 350 nm and with boron concentration ranging from 10 17 cm -3 to 10 21 cm -3 have been investigated. UV Raman spectroscopy and AFM have been used to assess the quality and morphology of the diamond films. Hall effect measurements confirmed the expected p-type conductivity. At room temperature, the conductivity varies from 1.5x10 -8 Ω -1 cm -1 for a non-intentionally doped film up to 76 Ω -1 cm -1 for a heavily B-doped film. Increasing the doping level results in a higher carrier concentration while the mobility decreases from 1.8 cm 2 V -1 s -1 down to 0.2 cm 2 V -1 s -1 . For NCD films with low boron concentration, the conductivity strongly depends on temperature. However, the conductivity and the carrier concentration are no longer temperature-dependent for films with the highest boron doping, and the NCD films exhibit metallic properties. Highly doped films show superconducting properties with critical temperatures up to 2K. The critical boron concentration for the metal-insulator transition is in the range from 2x10 20 cm -3 up to 3x10 20 cm -3 . We discuss different transport mechanisms to explain the influence of the grain boundaries and boron doping on the electronic properties of NCD films. Valence band transport dominates at low boron concentration and high temperatures, 2 whereas hopping between boron acceptors is the dominant transport mechanism for boron doping concentration close to the Mott transition. Grain boundaries strongly reduce the mobility for low and very high doping levels. However, at intermediate doping levels where hopping transport is important, grain boundaries have a less pronounced effect on the mobility. The influence of boron and the effect of grain boundaries on the optoelectronic properties of the NCD films are examined using spectrally resolved photocurrent measurements and photothermal deflection spectroscopy. Major differences occur in the low energy range, between 0.5 -1.0 eV, where both Boron impurities and the sp 2 carbon phase in the grain boundaries govern the optical absorption.

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Section: A Structural Propertiesmentioning

confidence: 99%

Section: B1 High Temperature Regimementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic and optical properties of boron-doped nanocrystalline diamond films

et al. 2009

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“…π-bonded states originated from GBs were reported to be responsible for the n-type conductivity in N-doped UNCD films with an activation energy below 10 meV. 15 As the measuring temperature increases to 400 o C, the corresponding activation energy increases to 0.05-0.15 eV. 45 It is likely that p-type conductivity is induced by the H-terminated diamond grains, while GBs induce n-type conductivity after hydrogen bondings decomposed at higher annealing temperature, which explains the p-type to n-type conductivity conversion from as-deposited sample to sample 900-A.…”

Section: (B)mentioning

confidence: 99%

“…15 This conductivity was due to the manipulation of the nanostructure of the material, leading to the enhanced sp 2 regions and midgap states in GBs. 16 Theoretical modelling also showed that nitrogen promoted π bonded states within the GBs, resulting in an impurity band near the Fermi level.…”

mentioning

confidence: 99%

An insight of p-type to n-type conductivity conversion in oxygen ion-implanted ultrananocrystalline diamond films by impedance spectroscopy

Coathup

et al. 2017

Applied Physics Letters

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The impedance spectroscopy measurements were used to investigate the separated contributions of diamond grains and grain boundaries (GBs), giving an insight of p-type to ntype conductivity conversion in O + -implanted ultrananocrystalline diamond (UNCD) films. It is found that both diamond grains and GBs promote the conductivity in O + -implanted UNCD films, in which GBs make at least half contribution. The p-type conductivity in O + -implanted samples is a result of H-terminated diamond grains, while n-type conductive samples is closely correlated to O-terminated O + -implanted diamond grains and GBs in the films. The results also suggest that low resistance of GBs is preferable to obtain high mobility n-type conductive UNCD film.

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