Photoluminescence and Raman studies of hydrogenated amorphous carbon films deposited by the rf plasma-enhanced CVD method

Chen, Chi-Lin; Lue, Juh Tzeng

doi:10.1016/0022-3093(95)00469-6

Cited by 7 publications

(3 citation statements)

References 17 publications

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“…It is known, however, that Ar + ions destroy the growing film and weaken the bonds more effectively than H + ions of the same energy. 23 According to the expectation, more drastic changes are observed in the chemical structure of the films deposited from TMGe and Ar compared to those obtained under the same conditions from pure TMGe. It is manifested by a band that emerges in the carbon region (spectrum d).…”

Section: Resultsmentioning

confidence: 90%

“…In deposition from pure TMGe (without Ar), a main role in the process is played by hydrogen ions (H + ). It is known, however, that Ar + ions destroy the growing film and weaken the bonds more effectively than H + ions of the same energy …”

Section: Resultsmentioning

confidence: 99%

“…[18][19][20][21] In general, visible Raman spectra of amorphous hydrogenated carbon films (a-C:H) show two characteristic peaks corresponding to the typical graphite G line centered at around 1580 cm -1 and the so-called disordered graphite D line centered around 1350 cm -1 . 18,[22][23][24][25] It is widely recognized that the former line originates from lattice vibrations in the plane of the graphite-like rings, whereas the latter line results from the disorderallowed zone-edge mode of graphite clusters. It is suggested, however, that these lines can be also associated with isolated benzene or condensed benzene rings.…”

Section: Introductionmentioning

confidence: 99%

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Transition from Amorphous Semiconductor to Amorphous Insulator in Hydrogenated Carbon−Germanium Films Investigated by Raman Spectroscopy

Kazimierski¹,

Tyczkowski²,

Kozanecki

et al. 2002

Chem. Mater.

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Amorphous hydrogenated carbon-germanium films (a-Ge X C Y :H) were fabricated by plasma chemical vapor deposition in an audio frequency (af) three-electrode reactor using tetramethylgermane (TMGe) as a source compound. Two types of the material, namely semiconducting (a-S) and insulating (a-I) films characterized by quite different electronic properties, were produced. For example, electrical conductivity at room temperature, T room , amounts to approximately 10 -18 S/m (with activation energy E A ≈ 0.9 eV) and 10 -4 S/m (E A ≈ 0.3 eV) for a-I and a-S, respectively. This very drastic change in the electronic structure of the a-Ge X C Y :H films can be caused by a very small variation of the plasma deposition conditions and therefore it is termed a-I-a-S transition. The previous attempts to explain the nature of the a-I-a-S transition from the molecular and supermolecular point of view (quantitative chemical microanalysis, XPS and IR spectrscopies, TEM, SEM, electron diffraction, and AFM) have failed. In this paper Raman spectroscopy has been used to this end. It has been found that the carbon structure does not determine the electronic properties of the films and sp 2 sites are not responsible for the a-I-a-S transition. This conclusion is supported by investigations on a-Ge X C Y :H films, in which sp 2 sites are purposely created. On the other hand, a drastic difference in the Ge atoms dispersion in the a-I and a-S has been found. In the a-I films a great amount of Ge atoms is molecularly dispersed, whereas in the a-S films the vast majority of Ge atoms is in the form of a-Ge several-nanometersized clusters. It is suggested that these clusters play a crucial role in the formation of the amorphous semiconductor network and they are responsible for the a-I-a-S transition.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 99%