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Titolo:
Anomalous Anderson transition in carbonized ion-implanted polymer p-phenylenebenzobisoxazole
Autore:
Du, G; Burns, A; Prigodin, VN; Wang, CS; Joo, J; Epstein, AJ;
Indirizzi:
Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Ohio State Univ Columbus OH USA 43210 , Dept Phys, Columbus, OH 43210 USA AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia AF Ioffe Phys Tech Inst St Petersburg Russia 194021 sburg 194021, Russia Univ Dayton, Res Inst, Dayton, OH 45469 USA Univ Dayton Dayton OH USA 45469 iv Dayton, Res Inst, Dayton, OH 45469 USA Ohio State Univ, Dept Chem, Columbus, OH 43210 USA Ohio State Univ Columbus OH USA 43210 , Dept Chem, Columbus, OH 43210 USA
Titolo Testata:
PHYSICAL REVIEW B
fascicolo: 15, volume: 61, anno: 2000,
pagine: 10142 - 10148
SICI:
1098-0121(20000415)61:15<10142:AATICI>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
LADDER POLYMERS; RIGID-ROD; ELECTRICAL-PROPERTIES; AMORPHOUS-CARBON; CONDUCTIVITY; SYSTEMS; FILMS; CHAIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Du, G Ohio State Univ, Dept Phys, Columbus, OH 43210 USA Ohio State Univ Columbus OH USA 43210 Phys, Columbus, OH 43210 USA
Citazione:
G. Du et al., "Anomalous Anderson transition in carbonized ion-implanted polymer p-phenylenebenzobisoxazole", PHYS REV B, 61(15), 2000, pp. 10142-10148

Abstract

We report a charge transport study which revealed an unusual insulator-metal transition in ion implanted polymer p-phenylenebenzobisoxazole. Upon ionimplantation, a carbonized layer forms on him sample surface and becomes increasingly conductive with increasing ion implantation dosage. A drastic change in the temperature dependence of conductivity sigma(T) with increasing ion dosage is observed at this transition. The row dosage samples (greater than or equal to 7X10(16) ions/cm(2)) have a low temperature insulating conductivity: sigma(T) similar to exp[-(T-0/T)(gamma)], where gamma was obtained at 0.74 increasing to 1/4 with increasing dosage. To explain the unusual value gamma = 0.74, we extend Mott's variable range hopping model by including in the consideration of an energy dependence of density of states near the Fermi level. This model also explains a temperature dependent conductivity near the insulator-metal transition in these low dosage dielectric samples. Ou the other hand, the high dosage samples(greater than or equal to10(17) ions/cm(2)) show a semimetallic conductivity: sigma(T) = sigma(0) Delta sigma(T), where Delta sigma(T) is due to electron-electron interaction and weak localization effects with the latter undergoing a dimensional crossover from three dimensions to two dimensions below similar to 40-50 K as reported earlier.

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Documento generato il 18/11/18 alle ore 05:27:53