Tunable conductivity and conduction mechanism in an ultraviolet light activated electronic conductor

Mariana I. Bertoni, Thomas O. Mason, Julia E. Medvedeva, Arthur J. Freeman, Kenneth R. Poeppelmeier, Bernard Delley

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

A tunable conductivity has been achieved by controllable substitution of an ultraviolet light activated electronic conductor. The transparent conducting oxide system H-doped Ca12-x Mgx Al14 O33 (x=0,0.1,0.3,0.5,0.8,1.0) presents a conductivity that is strongly dependent on the substitution level and temperature. Four-point dc-conductivity decreases with x from 0.26 Scm (x=0) to 0.106 Scm (x=1) at room temperature. At each composition the conductivity increases (reversibly with temperature) until a decomposition temperature is reached; above this value, the conductivity drops dramatically due to hydrogen recombination and loss. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Mg-substituted system with x=0, 1, and 2. The Seebeck coefficient is essentially composition and temperature independent, the later suggesting the existence of an activated mobility associated with small polaron conduction. The optical gap measured remains constant near 2.6 eV while transparency increases with the substitution level, concomitant with a decrease in carrier content.

Original languageEnglish
Article number103713
JournalJournal of Applied Physics
Volume97
Issue number10
DOIs
Publication statusPublished - May 15 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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