Epitaxial growth of β-FeSi2 thin films on Si(111) substrates by radio frequency magnetron sputtering and their application to near-infrared photodetection

β-FeSi2 thin films were epitaxially grown on p-type Si(111) substrates at a substrate temperature of 560 C and Ar pressure of 2.66 10^-1 Pa by radio-frequency magnetron sputtering (RFMS) using a sintered FeSi2 target, without postannealing. The resultant n-type β-FeSi2/p-type Si heterojunctions were evaluated as near-infrared photodiodes. Three epitaxial variants of β-FeSi2 were confirmed by X-ray diffraction analysis. The heterojunctions exhibited typical rectifying action at room temperature. At 300 K, the heterojunctions showed a substantial leakage current and minimal response for irradiation of near-infrared light. At 50 K, the leakage current was markedly reduced and the ratio of the photocurrent to dark current was considerably enhanced. The detectivity at 50 K was estimated to be 3.0 10¹¹ cm Hz^1/2/W at a zero bias voltage. Their photodetection was inferior to those of similar heterojunctions prepared using facing-target direct-current sputtering (FTDCS) in our previous study. This inferiority is likely because β-FeSi2 films prepared using RFMS are located in plasma and are damaged by it.