Enhanced photoluminescence from CdS with SiO2 nanopillar arrays

In this paper, the enhanced photoluminescence from CdS thin film with SiO2 nanopillar array (NPA) was demonstrated. The CdS was prepared using chemical bath deposition in a solution bath containing CdSO4, SC(NH2)2, and NH4OH. The SiO2 NPA was fabricated by the nanosphere lithography (NSL) techniques. The nanopillar is about 50 nm in diameter, and the height is 150 nm. As a result, the sample with NPA shows an obvious improvement of photoluminescence (PL), compared with the one without NPA. In addition, we also observed that the PL intensity is increased ~5 times if the active layer is deposited on the nanopillar arrays and covered by a thin metal film of Al. It is noteworthy that the enhancement of photoluminescence could be attributed to the roughness of the surface, the 2D photonic band gap (PBG) effect and the surface plasmon resonance (SPR) effects.