Textured thin-film Si solar selective absorbers using reactive ion etching

Solar selective surface photothermal absorbers consisting of thin-film Si with a submicron surface texture have been produced by reactive ion etching an evaporated Si film on a Mo layer. Such surfaces formed on 316 stainless steel and other substrates have solar absorptivities of 0.9 and calculated thermal emissivities of ∼0.2 at 200 °C. These selective surfaces are stable in air to 500 °C.