Electronic properties of CVD diamond

Nebel, Christoph E.

doi:10.1088/0268-1242/18/3/301

Cited by 131 publications

(88 citation statements)

References 52 publications

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“…At very low temperatures, the heavily boron doped NCD films show superconductivity. The variation of the conductivity with the boron concentration is in good agreement with the data previously reported for single-and polycrystalline diamond films: see for instance the reviews by Nebel, 22 Thonke 43 or Lagrange et al, 19,20 When discussing the effect of the boron doping on the electronic properties of diamond, most of the authors refer to a model initially proposed by Visser et al 17 and successfully applied later on by Borst and Weiss. 18 In this model, the conductivity can be described by the contribution of two main components: valence band conduction and hopping transport.…”

Section: B1 High Temperature Regimesupporting

confidence: 84%

“…22 Increasing the boron content in the gas phase results in a decrease of the apparent activation energy calculated in the high temperature region (the values of the activation energies are listed in Table I). For the heavily doped film (S12), with a boron concentration of 3.3x10 21 cm -3 , the activation energy is about 12 meV.…”

Section: B1 High Temperature Regimementioning

confidence: 99%

“…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. 23,24 Finally, the influence of the boron acceptor on the structural and optoelectronic properties of the diamond films were investigated for single and polycrystalline diamond films.…”

Section: Introductionmentioning

confidence: 99%

“…23,24 Finally, the influence of the boron acceptor on the structural and optoelectronic properties of the diamond films were investigated for single and polycrystalline diamond films. 21,22,[26][27][28][29][30][31] However, the same sort of detailed investigation is still missing for boron-doped NCD films. As it has been discussed for polycrystalline diamond films 22 and UNCD films, 32 it is essential to understand the influence of the grain boundaries on the optical properties of NCD and the role they play in the electronic transport.…”

Section: Introductionmentioning

confidence: 99%

“…21,22,[26][27][28][29][30][31] However, the same sort of detailed investigation is still missing for boron-doped NCD films. As it has been discussed for polycrystalline diamond films 22 and UNCD films, 32 it is essential to understand the influence of the grain boundaries on the optical properties of NCD and the role they play in the electronic transport. Recently, several papers have reported on the structural properties of NCD films, as revealed by Raman spectroscopy in low [33][34][35] and in high boron doped diamond films.…”

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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