Atomic layer deposited Pt coatings on NiTi thin films

Atomic layer deposited Pt coatings on NiTi thin films D. Vokoun, L. Kaderavek, J. Racek Department of Functional Materials, Institute of Physics of the ASCR, Prague, Czech Republic C.C. Kei, Y.S. Yu, N. Koothan Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, Taiwan In our previous studies, various ceramic atomic layer deposition (ALD) coatings preventing Ni-ion release were studied on NiTi samples for medical applications. ALD, based on self-limiting exchange reaction, can allow a single atomic layer growth in each ALD cycle at a low temperature (low temperature compatibility). ALD is considered as an attractive method to grow protective and bio-compatible coatings due to the precise thickness control, good coating conformity and adhesion, and low-temperature compatibility. Among protection coatings for medical applications, ductile Pt coating has a potential to withstand larger deformations than ceramic ones. In order to boost initial growth of Pt on NiTi, an Al2O3 underlayer by ALD is needed. In our study, the initial growth of Pt layer is evaluated in relation to Al2O3 underlayer thickness. In order to understand surface morphology and composition, Pt coatings on sputtered NiTi film/Si substrates are analyzed using atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) measurement, respectively.