Tetrahedrally bonded amorphous carbon (ta-C) thinfilm transistors

Clough, F.J.; Milne, W. I.; Kleinsorge, B.; Robertson, John; Amaratunga, G.A.J.; Roy, Biswadev

doi:10.1049/el:19960288

Cited by 70 publications

(18 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The result for the a-C device mentioned above is consistent with previous reports of three terminal devices at low electric fields [23,24]. In the previous reports, it was explained that a-C has a defect band below the Fermi level, with bandtail hopping occuring through these defects, and the Fermi level is modulated by the applied gate voltage.…”

Section: Discussionsupporting

confidence: 91%

“…The applied electric fields between source and drain are with relatively low electric field region, and therefore the conduction mechanism was attributed to conduction through localized states (via hopping), much like those found in conjugated polymers. [23][24][25] It was also reported that both the a-C and a-CN x thin film transistor (TFT) show p-type conduction through a band close to the edge of the extended states (σ band)…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing the band structure of hydrogen-free amorphous carbon and the effect of nitrogen incorporation

Miyajima

Tison

Giusca

et al. 2011

Carbon

View full text Add to dashboard Cite

Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Probing the band structure of hydrogen-free amorphous carbon and the effect of nitrogen incorporation

Miyajima

Tison

Giusca

et al. 2011

Carbon

View full text Add to dashboard Cite

“…Measurements on ta-C/Si heterojunctions, nitrogen doping data, and recently fabricated thin film transistors suggest E f lies below midgap and that undoped ta-C is p type. [34][35][36] Furthermore, electronic calculations suggest E f is pinned below the midgap by defect sites.…”

Section: B Properties Of Films Deposited At Ambient Temperaturementioning

confidence: 99%

Influence of ion energy and substrate temperature on the optical and electronic properties of tetrahedral amorphous carbon (ta-C) films

Chhowalla

Robertson

Chen

et al. 1997

Journal of Applied Physics

Self Cite

355

127

View full text Add to dashboard Cite

The properties of amorphous carbon ͑a-C͒ deposited using a filtered cathodic vacuum arc as a function of the ion energy and substrate temperature are reported. The sp 3 fraction was found to strongly depend on the ion energy, giving a highly sp 3 bonded a-C denoted as tetrahedral amorphous carbon ͑ta-C͒ at ion energies around 100 eV. The optical band gap was found to follow similar trends to other diamondlike carbon films, varying almost linearly with sp 2 fraction. The dependence of the electronic properties are discussed in terms of models of the electronic structure of a-C. The structure of ta-C was also strongly dependent on the deposition temperature, changing sharply to sp 2 above a transition temperature, T 1 , of Ϸ200°C. Furthermore, T 1 was found to decrease with increasing ion energy. Most film properties, such as compressive stress and plasmon energy, were correlated to the sp 3 fraction. However, the optical and electrical properties were found to undergo a more gradual transition with the deposition temperature which we attribute to the medium range order of sp 2 sites. We attribute the variation in film properties with the deposition temperature to diffusion of interstitials to the surface above T 1 due to thermal activation, leading to the relaxation of density in context of a growth model.

show abstract

“…These values are further justified as the mobility, close to the Fermi level, has been measured to be around 10 −9 -10 −6 m 2 V −1 s −1 . 14,15 Higher values of 1 -10 cm 2 V −1 s −1 have also been observed under special conditions of nanostructuring in the a-CN x films 16 and under superlattice conditions. 17 The small variation in the data as a function of substrate temperature is expected with the evolution of the bonding, especially the C-N sp 2 lone pair states and band gap.…”

mentioning

confidence: 81%

Highly photoconductive amorphous carbon nitride films prepared by cyclic nitrogen radical sputtering

Katsuno

Nitta

Habuchi

et al. 2004

Applied Physics Letters

View full text Add to dashboard Cite

We report on the growth of amorphous carbon nitride films ͑a-CN x ͒ showing the highest conductivity to date. The films were prepared using a layer-by-layer method ͑a-CN x :LL͒, by the cyclical nitrogen radical sputtering of a graphite radical, alternated with a brief hydrogen etch. The photosensitivity S of these films is 10 5 , defined as the ratio of the photoconductivity p to the dark conductivity d and is the highest value reported thus far. We believe that the carriers generated by the monochromatic light (photon energy 6.2 eV) in the a-CN x : LL films are primarily electrons, with the photoconductivity shown to increase with substrate deposition temperature. The family of tetrahedral amorphous carbon films has shown promise toward device applications based on luminescence. In particular, hydrogenated tetrahedral amorphous carbon has shown relatively good photoconducting properties, 1-3 which can be further improved by the addition of impurities such as nitrogen. 1,[4][5][6] The resulting amorphous carbon nitride films ͑a-C:N x ͒ show interesting properties, including electroluminescence, 7 photoluminescence, 8 low dielectric constant 9 and detection capability for heavy-ion particle. 10 The layer-by-layer amorphous carbon nitride films ͑a-CN x :LL͒ prepared in this study show a two to three orders of magnitude improvement in photoconductivity reported for any form of a-C films. We investigated the density , sp 3 fraction and nitrogen concentration [obtained using an electron-energy-loss spectroscopy (EELS)], the optical energy gap E 04 , the Urbach energy E U [calculated from photothermal deflection spectroscopy (PDS)], and defect density [from electron spin resonance (ESR)] as a function of substrate temperature T S during sputtering, in order to examine the thermal evolution of the growth and structure affecting the photoconductivity of these films.The a-CN x : LL films were prepared by a cyclic process of a deposition step of thin a-CN x film by a nitrogen radical sputtering, immediately followed by a hydrogen treatment step that helps to reconstruct the bulk material; this process is repeated until the required thickness of film is grown. The hydrogen treatment on the a-CN x films helps to reduce the defect density and remove weak C dangling bonds without the inclusion of significant atomic hydrogen. 4 The a-CN x films were prepared using sputtering in a 13.56 MHz rf system, at a power of 85 W, a substrate temperature T S that varies from room temperature (RT) to 400°C, and a N 2 sputter gas pressure of 0.12 Torr (gas purity of 99.999%). For the hydrogen treatment step, we used a glow discharge of H 2 at 0.50 Torr (gas purity 99.999%) at a rf power of 85 W at T S . The a-CN x films initially grown are reduced with structural reconstruction during this phase. Typical film thicknesses per layer for a single-sputter growth and etching cycle are estimated to be 15 and 5 nm, respectively, for a growth time of 3 min, followed by H 2 etching for 40 s. We ran seven cycles, resulting in a film thickness of 70 ...

show abstract

Tetrahedrally bonded amorphous carbon (ta-C) thinfilm transistors

Cited by 70 publications

References 5 publications

Probing the band structure of hydrogen-free amorphous carbon and the effect of nitrogen incorporation

Probing the band structure of hydrogen-free amorphous carbon and the effect of nitrogen incorporation

Influence of ion energy and substrate temperature on the optical and electronic properties of tetrahedral amorphous carbon (ta-C) films

Highly photoconductive amorphous carbon nitride films prepared by cyclic nitrogen radical sputtering

Contact Info

Product

Resources

About