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Ionic Space‐Charge Depletion in Lithium Fluoride Thin Films on Sapphire (0001) Substrates
Author(s) -
Li Chilin,
Guo Xiangxin,
Gu Lin,
Samuelis Dominik,
Maier Joachim
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201100303
Subject(s) - materials science , depletion region , lithium fluoride , sapphire , thin film , space charge , doping , condensed matter physics , fluoride , lithium (medication) , electromotive force , dielectric spectroscopy , ion , analytical chemistry (journal) , optoelectronics , semiconductor , inorganic chemistry , optics , nanotechnology , electrode , electron , chemistry , electrochemistry , medicine , laser , physics , quantum mechanics , chromatography , endocrinology
Lithium fluoride thin films with various thicknesses have been grown on c ‐plane sapphire substrates by radio‐frequency sputtering. The thin films are granular with a preferential [111] orientation of the grains. Thickness‐dependent measurements allow the separation of bulk and interface conductions. The normalized conductance decreases linearly with decreasing LiF layer thickness with a negative extrapolated intercept. DC polarization, AC impedance spectroscopy and electromotive force measurement indicate depletion of lithium ion vacancies as majority charge carriers and hence a negative space‐charge potential. A generalized Mott–Schottky approach within the model of heterogeneous doping fully explains the entire boundary defect chemistry.