Dielectric-MoS2 Interfaces Grown By Atomic Layer Deposition

Monday, 2 October 2017: 12:40
Chesapeake L (Gaylord National Resort and Convention Center)
S. Letourneau (Boise State University), A. U. Mane, J. W. Elam (Argonne National Laboratory), and E. Graugnard (Boise State University)
Molybdenum disulfide (MoS2) has become a prototypical transition metal dichalcogenide (TMDC) atomic-layered material because of its unique materials properties. For example, bulk MoS2 exhibits an indirect band-gap of 1.3 eV, while a single monolayer has a direct band-gap of 1.8 eV. Recently, nanometer scale transistor devices have been made with MoS2 and graphene, yet much of this work relies on layered materials prepared using chemical vapor deposition (CVD) and mechanically exfoliation. Multiple reports have demonstrated the growth of MoS2 via CVD, but only a few studies have reported MoS2 growth using atomic layer deposition (ALD), which offers potential advantages for high volume semiconductor manufacturing. Here, we report the ALD of few-layer MoS2 films using MoF6 and various sulfur precursors on various ALD-grown dielectric surfaces and the ALD of metal oxides on the ALD MoS2 films at temperatures between 100-300 °C. In particular, we used in-situ quartz crystal microbalance measurements to investigate the nucleation of MoS2 ALD on oxide surfaces and vice versa. In general, self-limiting growth of MoS2 was observed on a wide range of dielectric surfaces including alumina, magnesia, and hafnia. The ALD MoS2 films were amorphous as-deposited, but crystallized into a layered atomic structure upon annealing at 800 °C. Using in-situ spectroscopy and electrical measurements, growth inhibition of MoS2 was seen depending on the growth substrate. These studies provide insight into the low-temperature ALD of MoS2 and provide guidance for the ALD of additional TMDC films.