β-FeSi2 based metal-insulator-semiconductor devices formed by sputtering for optoelectronic applications

We fabricated β-FeSi2 films-based metal-insulator-semiconductor (MIS) devices to avoid influences of diffused iron in Si and at the same time to testify the ability of β-FeSi2 thin film as a promising optoelectronic material. β-FeSi2 films were prepared on Si(1 1 1) substrates using sputtering. MIS structures were fabricated by depositing a thin SiO2 layer (thinner than 10 nm) and then an aluminum film on SiO2 layer, in which Si was only used as the base for β-FeSi2 epitaxial growth. I-V measurements showed that rectifying features depend on the thickness of SiO2 layer and clear rectifying features were obtained from the devices with SiO2 layer thickness than 7.5 nm. Obvious photo response peaked at a wavelength around 1460 nm was obtained from the devices having SiO2 layer of about 5.0 and 7.5 nm. These results pave the way to the possible realization of a new β-FeSi2 optical sensor operating at 1500 nm.