Selenium and tellurium selective absorber coatings produced by an oblique vacuum deposition technique

Selective absorber surfaces with a/e ratios greater than 33:1 have been produced by the angled vapor deposition of Te thin films onto specular metal substrates. Such Te films have a remarkable surface texture structure which results in highly absorptive behavior for incident sunlight. The emissivity of the surface is determined by the specular substrate when the Te film is thin, thus producing the extremely high a/e ratio observed. The present work appears to yield substantially higher a/e ratios than those previously studied. Se, which also shows a distinctly different surface texture effect, was not found to yield a/e ratios greater than 2:1.