Surface distribution studies and improved photoluminescence characteristics of silica coated ZnS:Mn nanophosphor layers

Abstract

A simple methodology is presented for dispersing the silica-capped ZnS:Mn nanophosphors with controlled particle density as two-dimensional (2D) layers. Si wafer and borosilicate glass slides were taken as substrates for this method. Size-controlled ZnS:Mn nanoparticles were capped with silica for their surface passivation, growth retardation, and stabilization against environmental attacks. By varying the molar concentration of ZnS:Mn nanoparticles in silica sol, a controlled particle density on the substrates has been achieved. The morphological investigations of the layers showed that the surface distribution of the nanophosphor particles within the active area is uniform for a given molar concentration. The room-temperature photoluminescence (PL) studies of these layers showed a broad and intense peak at ∼593nm indicating a blueshift of about 7 nm compared to their conventional bulk counterparts due to quantum size effect. However, annealing of the layers improved the PL intensity by several orders attributing to the more efficient T14→A16 transitions of Mn in the nano-ZnS particles. The methodology presented of 2D layers is useful for microelectronics industry and for nanobased futuristic electroluminescent devices.