Luminescent YbVO4 by atomic layer deposition

Abstract

UV to visible and near-infrared converting thin films of YbVO₄ have been deposited by atomic layer deposition, using the precursor combinations Yb(thd)₃ (thd = 2,2,6,6-tetramethyl-3,5-heptanedione) and O₃, and VO(thd)₂ and O₃ at a deposition temperature of 240 °C, followed by post deposition annealing at 400–1000 °C. The UV absorption and the visible and near-infrared emission have been investigated in detail. The structure, thickness and composition of the deposited films have been studied by X-ray diffraction, ellipsometry, and X-ray fluorescence, respectively. The optimal pulse ratio of Yb(thd)₃ and VO(thd)₂ with respect to near-infrared emission was found to be 1 : 3, which also yielded the most crystalline sample after annealing. Crystallization of the films is accelerated when an excess of V₂O₅ is present, enabling crystallization at temperatures as low as 500 °C, probably through a flux aided process.