Amorphous nature of vacuum-deposited BiSb alloy films

Abstract

The dc resistivity and Hall coefficient have been measured between 300 and 77 K of the vacuum-deposited semimetallic Bi8 at % Sb alloy films. The observed resistivity ρ and Hall coefficient R are well represented by two terms 1 ρ = 1 ρ 0 + 1 ρ h and 1 R = 1 R 0 + 1 R h , respectively, where ρ 0 and r 0 are temperature independent, while ρ h and R h are temperature dependent. The temperature dependence of σ h (= 1 ρ h ) is found to obey an exp(− S T 1 4 ) law characteristic of variable range hopping conduction, indicating the presence of localized states. To confirm this, the ac conductivity has also been measured, the result being expressed as σ ∞ ω 0.5− ω 0.8. A qualitative band model for the amorphous state of the semimetallic films is presented to account for the experimental results.