Depth profile analysis of surface modified SnO2 gas sensors in a hollow cathode discharge

Depth profile analysis of a SnO2/SiO2/Si structure, modified with hexamethildisilazane and processed with rapid thermal annealing (RTA) in the temperature range of 800–1200 °C, is investigated in a hollow cathode discharge for the purpose of characterizing gas sensing solid state devices. The depth behavior of the elements tin, nitrogen, carbon and silicon in this structure is deduced from their emission spectra in the hollow cathode plasma. The hollow cathode used is a liquid nitrogen - cooled Al cylinder having 4 mm inner diameter and 12 mm length. Spectrally pure Ne at a pressure of 130 Pa is used as working gas. The hollow cathode discharge is supplied by a pulse generator with 10 μs pulse width, 4 kHz pulse frequency and 0.5 A pulse amplitude. The results are interpreted by possible reconstruction of hexamethyldisilazane molecule.