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The Metal‐Semiconductor Transition in Amorphous Si 1− x Cr x Films Detection of the Transition by Room‐Temperature Measurements
Author(s) -
Möbius A.
Publication year - 1987
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221440236
Subject(s) - amorphous semiconductors , condensed matter physics , semiconductor , ansatz , materials science , amorphous solid , transition metal , thermal conduction , phenomenological model , physics , chemistry , crystallography , optoelectronics , quantum mechanics , biochemistry , composite material , catalysis
The relation between σ and dσ/d T is studied at room‐temperature. All samples investigated, which show activated conduction at low temperatures, fulfil σ(293 K) < 360 Ω −1 cm −1 , whereas all samples with metallic conduction at low temperatures fulfil σ(293 K) > 440 Ω −1 cm −1 . Within the regions 100 to 360 Ω −1 cm −1 and 440 to 1400 Ω −1 cm −1 nearly linear relations between σ and dσ/d T are observed. It seems likely that dσ/d T as a function of σ exhibits a knee at about 420 Ω −1 cm −1 indicating the presence of a sharp metal‐semiconductor transition at room‐temperature. The experimental results confirm quantitatively a phenomenological model of σ( T , x ) in the semiconducting region, which is developed mainly on the basis of low temperature measurements in two preceding papers. On the other hand, doubts arise on the physical meaning of the ansatz α + β T 1/2 + γ T often used to analyse the metallic region at low T .