Epitaxial superlattices grown by a PLD-based continuous compositional-spread technique

A recently introduced continuous compositional-spread (CCS) technique-based on the non-uniformity of the deposition rate typically observed in pulsed laser deposition (PLD) is applied to the growth of epitaxial superlattices. This PLD–CCS method uses rapid (sub-monolayer) sequential deposition of the phase spread’s constituents, whereby a pseudo-binary or pseudo-ternary phase diagram can be deposited without the need for masks or a post-anneal. Consequently, combinatorial materials synthesis can be carried out under optimized film growth conditions (e.g., complex oxides can be grown at high-temperatures). Most importantly, lifting the requirement of a post-anneal to promote interdiffusion and crystallization renders this method applicable to the growth of epitaxial heterostructures. Results are shown for the case of superlattices consisting of a repeated stacking of SrTiO3 and (SrxBa1−x)ZrO3 layers, where the parameter x varies continuously across the sample. Because all of these samples are obtained in one single deposition, and because the approach is easily generalized to pseudo-ternary systems, the PLD–CCS method results in significant timesavings for studies of epitaxial superlattices.