Fabrication of n+-BaSi2/p+-Si Tunnel Junction on Si(111) Surface by Molecular Beam Epitaxy for Photovoltaic Applications

n + -BaSi 2 /p + -Si tunnel junctions with different BaSi 2 template layer thicknesses were grown by molecular beam epitaxy. The template was found to be indispensable for growing epitaxial n + -BaSi 2 , but the resistance of the junctions increased with template thickness. However, both epitaxial growth and low resistance were achieved for a template thickness of 1 nm. A current density of 21.9 A/cm 2 was achieved at 0.5 V. The photoresponsivity of 360-nm-thick undoped BaSi 2 grown on the tunnel junction increased with bias voltage and reached 74 mA/W at 2.3 eV under a reverse bias of 4 V, the highest value ever reported for semiconducting silicides.