Impact of substrate roughness on CuInxGa1−xSe2 device properties

In comparison to the traditional use of glass substrates, CuInxGa1−xSe2 (CIGS) deposited onto metal substrates offers improved device cooling under concentration, economical large-scale roll-to-roll processing, and applicability towards lightweight as well as flexible products. However, unlike glass, metal foils tend to exhibit rough surfaces. This study quantifies the effect of substrate roughness on CIGS device performance. Several substrate types with differing average roughnesses were examined. The frequencies of the surface features contributing to roughness are also examined via several different analytical techniques. Devices were prepared and characterized on steel foils, Mo foil, and glass.