Thin film deposition is key for optimising thermal imaging.

Thermal imagers - originally for military applications - are now used in many applications: from security and surveillance, through to determining the locations of people following fires and earthquakes. Devices like this are invaluable but materials scientists are looking to improve their performance. These devices' detector arrays consist of thin films of multi-component oxides with a perovskite-like crystal structure.

These large, mixed-metal oxide films need to be of high quality to produce good images but their manufacture remains a challenge to scientists. At the RSC's materials discussion meeting, held at the University of London, UK, in September, Peter Wright presented recent results. Wright, who works for QinetiQ, Malvern, UK, has been looking into the effect different compound mixes have when deposited as thin films.

The arrays studied were formed using various precursor compounds in conjunction with an advanced technique known as liquid-injection chemical vapour deposition. The compounds used - a mix of the appropriate metals required to form the thin film - were coordinated to a variety of different ligands to determine the effect they and different mixes of compounds had on the quality of the film. Wright found that controlling the effective stability of the different complexes used was very important. By modifying the initial coordination compounds, the efficiency of the all-important vaporisation step could be controlled along with the subsequent compound decomposition to form the films.

The main advantage of perovskite-type oxide thin films is their potential to be used in 'uncooled' thermal imagers. 'Uncooled' imagers do not require cryogenic cooling necessary for some current, high-resolution machines.

Vikki Allen