Metalorganic chemical vapor deposition of β-FeSi2 on β-FeSi2 seed crystals formed on Si substrates

We have fabricated a β-FeSi2 film by metalorganic chemical vapor deposition on a Si(001) substrate with β-FeSi2 seed crystals grown by molecular beam epitaxy, and investigated the crystallinity, surface morphology and temperature dependence of photoresponse properties of the β-FeSi2 film. The surface of the grown β-FeSi2 film was atomically flat, and step-and-terrace structure was clearly observed. Multi-domain structure of β-FeSi2 whose average size was approximately 200 nm however was revealed. The photoresponse was obtained in an infrared light region (~ 0.95 eV) at temperatures below 200 K. The external quantum efficiency reached a maximum, being as large as 25% at 100 K when a bias voltage was 2.0 V.