Electronic structure of SP2 trap states in amorphous carbon

Fotopoulos, N; Xanthakis, JP

dc.contributor.author	Fotopoulos, N	en
dc.contributor.author	Xanthakis, JP	en
dc.date.accessioned	2014-03-01T02:44:36Z
dc.date.available	2014-03-01T02:44:36Z
dc.date.issued	2007	en
dc.identifier.issn	0142-2421	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/31892
dc.subject	Amorphous carbon	en
dc.subject	Defect states	en
dc.subject	Electronic structure	en
dc.subject	Hartree-Fock	en
dc.subject	Trap states	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.other	Amorphous materials	en
dc.subject.other	Binding energy	en
dc.subject.other	Carbon	en
dc.subject.other	Defects	en
dc.subject.other	Electronic structure	en
dc.subject.other	Field emission cathodes	en
dc.subject.other	Transport properties	en
dc.subject.other	Amorphous carbon	en
dc.subject.other	Defect states	en
dc.subject.other	Molecular orbitals	en
dc.subject.other	Trap states	en
dc.subject.other	Electron traps	en
dc.title	Electronic structure of SP2 trap states in amorphous carbon	en
heal.type	conferenceItem	en
heal.identifier.primary	10.1002/sia.2475	en
heal.identifier.secondary	http://dx.doi.org/10.1002/sia.2475	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	Amorphous carbon, a-C : H, contains an unusually high number of defect states, typically 10(19)/cm(3). These states play a major role in the process of field electron emission from a-C : H since they inhibit (by trapping) the transport of electrons from the cathode to the amorphous carbon film/vacuum interface. In this paper we examine the electronic structure of two of these defects, the pentagon-heptagon pair and a broken carbon double bond (by the addition of one hydrogen at one of the two carbon atoms). These defects are expected to be found in a graphitic environment in a-C : H. To obtain their electronic structure, we construct large enough graphitic clusters, embed the defects at their center and then use typical semiempirical quantum chemical methods such as the PM3 method - which is a parameterized Hartree-Fock method - to calculate the energy levels in the gap and the binding energies. Both defects produce energy levels just above the highest occupied molecular orbital (HOMO) of the graphite levels, but the pentagon-heptagon pair has a much higher binding energy, making it more stable. From the difference in binding energy, we conclude that the pentagon-heptagon pair is far more stable. Copyright (C) 2007 John Wiley & Sons, Ltd.	en
heal.publisher	JOHN WILEY & SONS LTD	en
heal.journalName	Surface and Interface Analysis	en
dc.identifier.doi	10.1002/sia.2475	en
dc.identifier.isi	ISI:000244295600010	en
dc.identifier.volume	39	en
dc.identifier.issue	2-3	en
dc.identifier.spage	132	en
dc.identifier.epage	134	en