Enhanced outcoupling of electroluminescence from ZnS:ErF3 thin films by a photonic crystal

Abstract

Enhanced 1550 nm near-infrared emission due to a photonic crystal (PC) in zinc sulfide (ZnS) doped with erbium trifluoride (ErF3) has been studied in sputter deposited alternating current thin film electroluminescent (ACTFEL) devices. The honeycomb structured PC was fabricated into the ZnS:ErF3 layer by electron beam lithography and argon sputtering. A thin film of yttria-stabilized zirconia (YSZ) was deposited into the honeycomb structure of holes, creating the photonic crystal structure with a dielectric constant mismatch between the ZnS:ErF3 layer and the YSZ of approximately 20. The photonic band gaps were modeled for different values of dielectric mismatch and the honeycomb structure hole diameter and lattice spacing. For the 1550 nm wavelength, the lattice constant and hole diameter typically were ∼748 and ∼342 nm, respectively. The YSZ structured PC ACTFEL device showed a twofold increase in 1550 nm light intensity versus a device without a PC structure. These results could not be explained by clas...