CUED Publications database

Tetrahedral amorphous carbon-silicon heterojunction band energy offsets

Rupesinghe, NL and Cole, RJ and Chhowalla, M and Amaratunga, GAJ and Weightman, P (2000) Tetrahedral amorphous carbon-silicon heterojunction band energy offsets. Diamond and Related Materials, 9. pp. 1148-1153. ISSN 0925-9635

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Non-hydrogenated tetrahedral amorphous carbon (ta-C) has shown superior field emission characteristics. The understanding of the emission mechanism has been hindered by the lack of any directly measured data on the band offsets between ta-C and Si. In this paper results from direct in situ X-ray photoemission spectroscopy (XPS) measurements of the band-offset between ta-C and Si are reported. The measurements were carried out using a filtered cathodic vacuum arc (FCVA) deposition system attached directly to an ultra-high vacuum (UHV) XPS chamber via a load lock chamber. Repeated XPS measurements were carried out after monolayer depositions on in situ cleaned Si substrates. The total film thickness for each set of measurements was approximately 5 nm. Analysis of the data from undoped ta-C on n and p Si show the unexpected result that the conduction band barrier between Si and ta-C remains around 1.0 eV, but that the valence band barrier changes from 0.7 to 0.0 eV. The band line up derived from these barriers suggests that the Fermi level in the ta-C lies 0.3 eV above the valence band on both p and n+Si. The heterojunction barriers when ta-C is doped with nitrogen are also presented. The implications of the heterojunction energy barrier heights for field emission from ta-C are discussed.

Item Type: Article
Divisions: Div B > Electronics, Power & Energy Conversion
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:34
Last Modified: 18 Feb 2021 15:27
DOI: 10.1016/S0925-9635(00)00195-3