SURFACE TEXTURING OF COPPER BY SPUTTER ETCHING WITH APPLICATIONS FOR SOLAR SELECTIVE ABSORBING SURFACES

Solar selective absorbing surfaces have been produced by texturing copper specimens in a novel magnetron cosputtering system which permits high rate sputter etching of a moving metal plate seeded with low sputter rate material. Unusual topographical features have been produced on copper in this apparatus using titanium seed. The variation of optical properties and surface morphology of the copper as a function of sputter etching conditions has been investigated. Typical selective surfaces produced have absorptances alpha approximately equals 0. 90 and emittances epsilon approximately equals 0. 10 at 300 K.