Photoresponse properties of BaSi2 epitaxial films grown on the tunnel junction for high-efficiency thin-film solar cells

We have successfully grown 360-nm-thick undoped n-BaSi2 epitaxial layers on the n+-BaSi2/p+-Si(111) tunnel junction, by molecular beam epitaxy. The external quantum efficiency reached approximately 17.8% at 500 nm under a reverse bias voltage of 4 V at room temperature, the highest value ever reported for semiconducting silicides. The quantum efficiency was compared to 240-nm-thick undoped n-BaSi2 epitaxial layers on a p-Si(111) substrate.