Subgap absorption study of chemical vapor deposited thin diamond films

Zammit, U.; Marinelli, M.; Mercuri, F.; Foglietta, S.

doi:10.1103/physrevb.57.4518

Cited by 5 publications

(11 citation statements)

References 18 publications

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“…II. Some of these lines which were found by deconvolution, had been reported before and some had not [1][2][3]5,6,8,[11][12][13]15,18]. We will come to this point later.…”

Section: Introductionmentioning

confidence: 68%

Jahn-Teller effect in diamond-like carbon

Vesaghi

Shafiekhani

1999

J. Phys. D: Appl. Phys.

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The Jahn-Teller effect used semi-theoretically to analyse UV-visible spectra of the diamond like-carbon films on Si substrates. By deconvolution of UV-visible absorption spectra of the typical films, different absorption lines found. For each sample, six lines which were related to V • by Jahn-Teller effect are distinguished. Our theoretical approach based on distortion of the V • as the consequence of the stress in the films, is in agreement with experimental results. The shift of the Jahn-Teller lines toward the zero phonon line of V • were found in accordance to stress decrease in the films. The difference between room temperature and low temperature spectra is discussed. We found that the splitting of the excited state of V • in the films under stress is twice as large as that of the ground state.

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“…II. Some of these lines which were found by deconvolution, had been reported before and some had not [1][2][3]5,6,8,[11][12][13]15,18]. We will come to this point later.…”

Section: Introductionmentioning

confidence: 68%

Jahn-Teller effect in diamond-like carbon

Vesaghi

Shafiekhani

1999

J. Phys. D: Appl. Phys.

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“…The exemplary densityof-state curves for a polycrystalline diamond film calculated using the fitting parameters taken from Ref. 58 for one particular sample labeled 860-20 are shown in Fig. 3.…”

Section: B Density-of-states Modelmentioning

confidence: 99%

“…The effect of nitrogen on the position of the Fermi level in the fundamental band gap has been discussed in the literature. 24,25 Since we rely on the density-ofstates model to be symmetric about the fundamental-gap center, 24,58,63 the charge neutrality condition requires that the Fermi level coincides with the midgap energy. Under this assumption, the midgap density of states and electron concentration are defined by the degree of overlapping between the π and π * bands.…”

Section: B Density-of-states Modelmentioning

confidence: 99%

“…63 To describe σ − σ * bands, we use the parameters E m , E 0 , and B 2 typical for polycrystalline diamond films per Ref. 58. The choice of these parameters though is not expected to affect the resulting FE characteristics significantly.…”

Section: Application Of Poisson's and Stratton's Equations To Sp 2mentioning

confidence: 99%

“…. In the literature,57,58,63 describing subgap absorption in polycrystalline carbonic materials, coefficients B 1 ∝ K…”

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confidence: 99%

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Theoretical evaluation of electronic density-of-states and transport effects on field emission from n-type ultrananocrystalline diamond films

Chubenko

Baturin

Baryshev

2019

Journal of Applied Physics

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In the nitrogen-incorporated ultrananocrystalline diamond ((N)UNCD) films, representing an n-type highly conductive two-phase material comprised of sp 3 diamond grains and sp 2rich graphitic grain boundaries, the current is carried by a high concentration of mobile electrons within the large-volume grain boundary networks. Fabricated in a simple thinfilm planar form, (N)UNCD was found to be an efficient field emitter capable of emitting a significant amount of charge starting at the applied electric field as low as a few V/µm which makes it a promising material for designing electron sources. Despite the semimetallic conduction, field emission (FE) characteristics of this material demonstrate a strong deviation from the Fowler-Nordheim law in a high-current-density regime when (N)UNCD field emitters switch from a diode-like to resistor-like behavior. Such phenomenon resembles the currentdensity saturation effect in conventional semiconductors. In the present paper, we adapt the formalism developed for conventional semiconductors to study current-density saturation in (N)UNCD field emitters. We provide a comprehensive theoretical investigation of (i) the influence of partial penetration of the electric field into the material, (ii) transport effects (such as electric-field-dependent mobility), and (iii) features of a complex density-of-states structure (position and shape of π−π * bands, controlling the concentration of charge carriers) on the FE characteristics of (N)UNCD. We show that the formation of the current-density saturation plateau can be explained by the limited supply of electrons within the impurity π − π * bands and decreasing electron mobility in high electric field. Theoretical calculations are consistent with experiment.

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The role of charge trapping at grain boundaries on charge transport in polycrystalline chemical vapor deposited diamond based detectors

Hearne

Trajkov

Jamieson

et al. 2006

Journal of Applied Physics

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We report a detailed investigation of the trapping and release of charge carriers from grain boundaries in polycrystalline diamond grown by chemical vapor deposition (poly-CVD). A model for charge trapping and release is presented for samples which display very different bulk characteristics as determined by photoluminescence, dark conductivity, and thermally stimulated current measurements. Experimental studies were performed as a function of temperature and applied electric field using ion beam induced charge to map the charge collection efficiency of charge induced by a scanned, focused, 2MeV He+ microprobe. Even though the carrier velocity and charge collection efficiency should begin to saturate at electric fields above 1×104V∕cm, the efficiency was found to increase by a factor of 3 when the electric field is increased to greater than 1×105V∕cm. A model based on the localized enhancement of the electric field caused by trapped charge at grain boundaries is found to account for this unexpected result. Further, we find that this localized variation in electric field strongly affects charge transport in poly-CVD diamond and is therefore an important consideration for optimizing detector performance.

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Subgap absorption study of chemical vapor deposited thin diamond films

Cited by 5 publications

References 18 publications

Jahn-Teller effect in diamond-like carbon

Jahn-Teller effect in diamond-like carbon

Theoretical evaluation of electronic density-of-states and transport effects on field emission from n-type ultrananocrystalline diamond films

The role of charge trapping at grain boundaries on charge transport in polycrystalline chemical vapor deposited diamond based detectors

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