In situ preparation of YH2 thin films by PLD for switchable devices

Abstract

We prepared epitaxial YH2 films on (111) CaF2 by pulsed laser deposition (PLD) from a metallic yttrium target. Without adding any reactive hydrogen, the dihydride is formed in situ due to the hydrogen evolving from the metallic target which contains ~7 at% H. Upon pulsed laser irradiation, the target acts as a pulsed source of both yttrium and hydrogen. The increased hydrogen content of the film as compared to the target is explained to be due to diffusion assisted preferential ablation of hydrogen. Due to this deposition process the hydrogen load on the deposition system is minimized, which is important in view of the fabrication of hydride/oxide stacks for all-solid-state switchable mirror devices. Furthermore, the preparation of both nanocrystalline and epitaxial YH2 films shows the versatility of the PLD process.