Control of the Conduction Type of Nondoped High Mobility β-FeSi₂ Films Grown from Si/Fe Multilayers by Change of Si/Fe Ratios

Abstract

Highly [100]-oriented nondoped β-FeSi 2 continuous films were grown on Si (001) substrates from Si/Fe multilayers with different Si/Fe ratios (1.6–2.0). It was found that the conduction type of the grown layer changed from p-type to n-type when the deposited Si/Fe ratio was increased, suggesting that the conduction type of nondoped β-FeSi 2 is governed by stoichiometry. Annealing of the samples at 900°C for up to 14 h decreased the carrier density and increased the mobility, but did not change the conduction type. A p-type sample gave the highest hole mobility ever reported; 13000 cm 2 /V·s at 50 K.