MoS₂ deposited by ion beam assisted deposition: 2H or random layer structure?

The structure of MoS₂ films grown by ion beam assisted deposition is investigated using transmission electron microscopy. Films consist of stacks of S–Mo–S planes with a [001] texture; however, three-dimensional crystal symmetry is disrupted by a high density of planar defects. Selected area electron diffraction patterns show (hk0) and (00l) reflections, features similar to a random layer structure, as well as diffuse (103) reflections. It is suggested that these films do not have a true random layer structure, but rather a two-dimensional structure formed by nonrandom in-plane translations.