Localized and nonlocalized impurity states in amorphous germanium

The purpose of this study was to investigate which impurities form localized states in amorphous Ge and to study the concentration dependence of the effect. The low temperature resistivity of amorphous alloy films deposited at 77°K was well fitted by the relation $\text{ρ = ρ}{}_{\mathrm{<mtext>0\; </mtext><mtext>exp</mtext>}}\text{[(}\text{T}{}_0\text{T}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{]}$. The increase in the number of localized states resulting from an increase in the number of impurities is evidenced by a decrease in T₀ Impurities which lead to shallow energy levels in the crystalline form do not form localized states near the Fermi level while impurities with deep lying levels do.