Magnetic properties of low temperature grown Si:Ce thin films on [001] Si substrate by molecular beam epitaxy

A diluted magnetic semiconductor, Si:Ce thin films with the Ce concentration below 4.3 at%, were prepared by solid source molecular beam epitaxy. The lattice constant of the Si:Ce film increases with increasing the Ce concentration, while it decreases above Ce 0.2 at%. Magnetization measured at 4.2 K for the samples with the Ce concentration up to 0.2 at% also increases with increasing the Ce concentration up to 0.2 at%. The amount of substituted Ce in Si is considered to play an important role for the magnetic properties.