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Scandium thin films‐structure and electrical resistance (I). A study on films obtained in a vacuum of 10 −5 up to 10 −6 Torr
Author(s) -
Loboda V. B.,
Protsenko I. E.,
Yaremenko A. V.
Publication year - 1980
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19800150108
Subject(s) - torr , annealing (glass) , scandium , analytical chemistry (journal) , thin film , materials science , ultra high vacuum , chemistry , nanotechnology , metallurgy , physics , chromatography , thermodynamics
A structure as well as a specific electrical resistance of scandium films having a various thickness (300 up to 2800 Å) obtained at a condensation rate: w ⋍ 1 up to 155 Å/s have been studied in the present work. Depending on condensation conditions in films a hydride ScH x , h.c.p. — Sc, or ScH x + Sc alternatively, is formed, a phase containing a distorted hexagonal lattice evolving into the ScH x over a period of a few hours. The ScH x and h.c.p‐Sc change to Sc 2 O 3 when annealed in a vacuum of 5 · 10 −5 Torr at a T ≈ 800°C, while in a vacuum of 3 · 10 −8 Torr a change to h.c.p.‐Sc with negligible inclusions of oxidic Sc 2 O 3 particles takes place. Formation of oxide is observed also when heating the films with an electron beam directly in a microscope under vacuum of ∼ 8 · 10 −5 Torr. The specific electrical resistance ϱ of the film just after a condensation has taken place is approximatly by an order higher as against the ScH x ‐ and h.c.p.‐Sc solid specimens. An irreversible gain in said resistance is observed while holding at a room temperature or annealing in a vacuum of 5 · 10 −5 Torr, this being associated with absorption of H 2 , O 2 and, possibly, of water steam, and then with formation of Sc 2 O 3 . Annealing in a vacuum of 5 · 10 −8 up to 10 −7 Torr involves a temperature relationship for ϱ of an intricated nature, this being accounted for by a structure transition as follows:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm ScH}_{{\rm x,}} \,{\rm Sc}\,\, \to \,{\rm Sc}\, + \,{\rm Sc}_2 O_3 . $$\end{document} A diode‐effect diminishing with a temperature rise is observed in annealed films.