Strong (110) Texturing and Heteroepitaxial Growth of Thin Mo Films on MoS2 Monolayer

Growth of textured and low-resistivity metallic seed layers for AlN-based piezoelectric films is of high importance for bulk acoustic wave resonator applications. Through optimization of Mo physical vapor deposition parameters, namely, the Ar flow rate, strong (110) texturing and low electrical resistivities (similar to 3 x 10(-7) Omega m) were observed for 43 +/- 3 nm thick Mo films on a CVD-grown MoS2 monolayer on c-Al2O3(0001) substrates. The strong texturing was attributed to the growth template effect of the monolayer MoS2 due to the presence of a local epitaxial relationship between (110)-Mo and (0001)-MoS2 (i.e., through MoS2(0001)[11 (2) over bar0]parallel to Mo(110)[(1) over bar 11] and/or MoS2(0001)[11 (2) over bar0]parallel to Mo(110)[001]), coupled with an atomic-scale flatness of the MoS2 surface, which promotes layer-by-layer growth of the Mo film. The deposited Mo/MoS2 monolayer stack can also be easily peeled-off from the growth Al2O3(0001) substrate for possible subsequent transfers onto arbitrary substrates (e.g., SiO2/Si(001)) due to a weak van der Waals coupling at the MoS2 and Al2O3(0001) interface, facilitating vertical stacking strategies for monolithic integration of high quality and therefore high-performance, AlN-based piezoelectric devices and sensors on the Si platform.

Automated summary

By optimizing the physical vapor deposition parameters of Mo, textured and low-resistivity Mo films were obtained on CVD-grown MoS2 monolayers. The presence of a local epitaxial relationship between (110)-Mo and (0001)-MoS2, as well as the atomic-scale flatness of the MoS2 surface, contributed to the strong texturing and layer-by-layer growth of the Mo film. The deposited Mo/MoS2 stack can be easily peeled-off from the substrate, enabling potential transfers onto arbitrary substrates.