Van der Waals epitaxy of continuous thin films of 2D materials using atomic layer deposition in low temperature and low vacuum conditions

Abstract

Van der Waals epitaxy holds great promise in producing high-quality films of 2D materials. However, scalable van der Waals epitaxy processes operating at low temperatures and low vacuum conditions are lacking. Herein, atomic layer deposition is used for van der Waals epitaxy of continuous multilayer films of 2D materials HfS2, MoS2, SnS2, and ZrS2 on muscovite mica and PbI2 on sapphire at temperatures between 75 degrees C and 400 degrees C. For the metal sulfides on mica, the main epitaxial relation is MS2 mica. Some domains rotated by 30 degrees are also observed corresponding to the MS2 mica alignment. In both cases, the presence of domains rotated by 60 degrees (mirror twins) is also expected. For PbI2 on sapphire, the epitaxial relation is PbI2 Al2O3 with no evidence of 30 degrees domains. For all of the studied systems there is relatively large in-plane mosaicity and in the PbI2/Al2O3 system some non-epitaxial domains are also observed. The study presents first steps of an approach towards a scalable and semiconductor industry compatible van der Waals epitaxy method.