Surface-plasmon-induced light absorption on a rough silver surface

Abstract

We investigate light absorption in metal films, silver and aluminum, with different surface roughness. Measurements using an integrating sphere show that the reflectance in silver decreases significantly with increasing surface roughness whereas the reflectance in aluminum is almost constant. The experimental results agree well with numerical simulations in which the surface roughness of metal is described properly. In particular, the simulations demonstrate that the absorption by surface-plasmon-polaritons excited on a rough silver surface causes the surface-dependent reflectance in silver. This study suggests a convenient and feasible rule to rationally design a backside metal reflector toward high-efficiency light-emitting diodes and photovoltaics.