Paper AS-MoM6
Simultaneous XPS-UPS Depth Profiling of Thin Films

Monday, November 7, 2016, 10:00 am, Room 101B

Thin films have found use in the fields of microelectronics, coatings and photovoltaics, amongst others and continued research is of vital importance in order to improve their performance in these applications. X-ray Photoelectron Spectroscopy (XPS) is a long established technique for analysing these types of samples due to its chemical specificity and surface sensitivity. The closely related technique, Ultraviolet Photoelectron Spectroscopy (UPS), has also been widely utilised to provide detailed valence electronic information with greater surface specificity than XPS, due to the incident radiation being of lower energy.

While useful information is acquired from XPS and UPS in isolation, a more powerful insight into the structure of a material comes from using these two techniques in conjunction, allowing a more complete material characterisation to be performed. Previously, switching between techniques throughout the course of an experiment has been an involved and often laborious process, discouraging more widespread use. Recently the automation of UPS has allowed concurrent acquisition of XPS and UPS data during depth profiling, providing a much sought after insight into the correlation between chemical and electronic structure at within a substrate at various depths.

Of particular interest is the ability to access the valence electronic structure at mixed oxide interfaces using small argon ion gas clusters, which was not previously possible due to the loss of electronic structure in semiconductors or organic materials on exposure to monatomic argon ion beams. This presentation demonstrates the wealth of information that can be acquired by performing XPS-UPS depth profiles and the ease with which this information can be acquired and processed, due to recent instrumentation and software developments.