Surface Engineering Using Self-assembled Monolayers: Model Substrates for Atomic-layer Deposition

Conclusion

The role of the initial surface on ALD of WC_xN_y can be investigated using SAMs as model substrates. SAMs provide films of known chemical composition with macroscopically well-ordered surfaces. With thermal stability extending from 500–600° C, such substrates withstand multiple cycles of ALD at 300°C. Comparis of WC_xN_y grown on SAMs with methyl-, bromo-, and cyano-terminal groups and alkyl chain lengths ranging from 7 to 17 methylene units shows differences in tungsten coverage, film thickness, density, resistivity, and interfacial and surface structure. The terminal group and the alkyl chain length both influence the observed growth behaviour. The cyano-terminated SAM is most promising for WC_xN_y growth. Overall, this study demonstrates that via tunable structure and surface chemistry, SAMs represent a novel approach to surface engineering and provide model substrates for atomic layer deposition.