Excimer Laser Liftoff of Epitaxial Pb(Zr,Ti)O3 Thin Films and Heterostructures

Abstract

AbstractEpitaxial (100) and (111)-oriented Pb(Zr,Ti)O3-based thin films and heterostructures have been transferred intact from their sapphire and MgO growth substrates to silicon and polymer substrates utilizing a novel laser liftoff process. The heterostructures, while on their growth substrate, were bonded to the receptor substrates using one of several bonding methods, including van der Waals bonding to an elastomer receptor, and transient liquid-phase Pd-In bonding to Si. A single 38 ns pulse from a KrF excimer laser (<,= 248 nm) directed through the transparent growth substrate induced localized heating of the perovskite interfacial layer. At fluences corresponding to the onset of vaporization (>300 mJ/cm2), the sapphire or MgO substrate was detached. Because of the short pulse length and the low thermal conductivity of Pb-based perovskite phases, heating of the top surface of the heterostructure was minimal, thus permitting film transfer to thermally-sensitive receptor substrates. X-ray rocking curves revealed slight broadening of the principal PLZT diffraction peaks (∼10–20%), suggesting local relaxation of film stress.