Characterization of boron doped CVD diamond films by Raman spectroscopy and X-ray diffractometry

Gonçalves, J.A.N.; Sandonato, G. M.; Iha, Koshun

doi:10.1016/s0925-9635(02)00103-6

Cited by 32 publications

(13 citation statements)

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“…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%

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: Introductionmentioning

confidence: 99%

Electronic and optical properties of boron-doped nanocrystalline diamond films

et al. 2009

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“…For the production of diamond and DLC coatings with vapor deposition processes, it is believed that substrate temperature and bias, gas type and flow rate, and substrate material are predominant parameters in determining the structure, morphological characteristics, and residual stress level of the coatings. [2][3][4][5][6] It was reported that direct current plasma jet ͑DCPJ͒ diamond coatings had an internal stress gradient along the radial direction of sample surface. 7 The internal stress of microwave chemical-vapor-deposited ͑MWCVD͒ diamond coatings was also investigated.…”

Section: Introductionmentioning

confidence: 99%

Residual stresses of diamond and diamondlike carbon films

Liu

Blanpain

et al. 2005

Journal of Applied Physics

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This paper evaluated the internal stresses of different diamond and diamondlike carbon ͑DLC͒ coatings. For the diamond coatings, the stresses were determined using micro-Raman spectroscopy and x-ray diffraction ͑XRD͒, while the stresses of DLC films were determined with bent plate method. The internal stress was related to the structural properties of the coatings. Direct current plasma jet, combustion flame, and microwave chemical-vapor deposition processes were used to prepare the diamond coatings on the tungsten carbide or molybdenum substrates, while the DLC films were deposited on the silicon wafers with filtered cathodic vacuum arc process. From the Raman spectra of the diamond coatings, the compressive internal stresses were determined, which were related to the microstructure of the coatings. The results from XRD were comparable with those obtained from micro-Raman spectroscopy. Higher compressive residual stresses in the DLC films were noticed, which were also related to their chemical bonding nature as well as their microstructures.

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“…The diamond films were grown on monocrystalline silicon (111) by hot filament CVD in a 10-cm-diameter, 30 cm long cylindrical quartz reactor [10]. Boron was introduced into the reactor by flowing hydrogen through the B 2 O 3 methanol solution.…”

Section: Methodsmentioning

confidence: 99%

Experimental study of vacuum diodes under partial space-charge regime

Gonçalves

Barroso

Sandonato

2004

Diamond and Related Materials

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Supported by analytical considerations and experimental verification, we demonstrate that thermionic electron current under partial space-charge condition follows the threehalves power Child-Langmuir law with a proportionality coefficient, j, that is material dependent and characterizes the emitter unambiguously. Such a partial space-charge regime has been assessed through experiments on parallel plane diodes with borondoped diamond films (with four different B/C ratios) as electron emitters at temperature of 1000 K. All current measurements have indicated a 3/2-power relationship on voltage but with distinct, material dependent coefficients j that were found to decrease with the work function of the samples tested.

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Characterization of boron doped CVD diamond films by Raman spectroscopy and X-ray diffractometry

Cited by 32 publications

References 13 publications

Electronic and optical properties of boron-doped nanocrystalline diamond films

Electronic and optical properties of boron-doped nanocrystalline diamond films

Residual stresses of diamond and diamondlike carbon films

Experimental study of vacuum diodes under partial space-charge regime

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