Compositional dependence of epitaxial Ti n+1 SiC n MAX-phase thin films grown from a Ti 3 SiC 2 compound target

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2019-03, Vol.37 (2)
• Main Authors: Magnuson, Martin, Tengdelius, Lina, Greczynski, Grzegorz, Eriksson, Fredrik, Jensen, Jens, Lu, Jun, Samuelsson, Mattias, Eklund, Per, Hultman, Lars, Högberg, Hans
• Format: Article
• Language: English
• ISSN: 1520-8559; 0734-2101
• DOI: 10.1116/1.5065468

The authors investigate sputtering of a Ti 3 SiC 2 compound target at temperatures ranging from RT (no applied external heating) to 970 °C as well as the influence of the sputtering power at 850 °C for the deposition of Ti 3 SiC 2 films on Al 2 O 3 (0001) substrates. Elemental composition obtained from time-of-flight energy elastic recoil detection analysis shows an excess of carbon in all films, which is explained by differences in the angular distribution between C, Si, and Ti, where C scatters the least during sputtering. The oxygen content is 2.6 at. % in the film deposited at RT and decreases with increasing deposition temperature, showing that higher temperatures favor high purity films. Chemical bonding analysis by x-ray photoelectron spectroscopy shows C–Ti and Si–C bonding in the Ti 3 SiC 2 films and Si–Si bonding in the Ti 3 SiC 2 compound target. X-ray diffraction reveals that the phases Ti 3 SiC 2 , Ti 4 SiC 3 , and Ti 7 Si 2 C 5 can be deposited from a Ti 3 SiC 2 compound target at substrate temperatures above 850 °C and with the growth of TiC and the Nowotny phase Ti 5 Si 3 C x at lower temperatures. High-resolution scanning transmission electron microscopy shows epitaxial growth of Ti 3 SiC 2 , Ti 4 SiC 3 , and Ti 7 Si 2 C 5 on TiC at 970 °C. Four-point probe resistivity measurements give values in the range ∼120 to ∼450  μ Ω cm and with the lowest values obtained for films containing Ti 3 SiC 2 , Ti 4 SiC 3 , and Ti 7 Si 2 C 5 .