High throughput thin film materials science

Combinatorial techniques, in which a library of chemical formulations is scanned for specific activity, have been used extensively to expedite the discovery phase of pharmaceutical compounds. Such techniques have more recently come to prominence in relation to the discovery of novel functional inorganic materials using methods of thin film deposition. Here the aim is to prepare a thin film sample containing a spread of compositions so that localised measurements can explore a range of properties across the phase diagram. The application of high throughput thin film techniques to the optimisation of materials properties has its roots in earlier studies which exploited position-dependent process variables to assist optimisation protocols. Indeed, we argue here that one of the biggest challenges facing combinatorial materials science is to ensure that property variations can be ascribed solely to composition changes, by achieving sufficient control over the inevitable variation in other process parameters. This review provides a discussion of the range of parameters, including composition, which can be controllably varied as a function of position during thin film growth. In addition to the growth techniques themselves, we discuss the requirements placed on materials diagnostics and property measurements, which are essential for the high throughput capability to be realised.