title: HfO(2) on MoS(2) by atomic layer deposition: adsorption mechanisms and thickness scalability.
abstract: We report our investigation of the atomic layer deposition (ALD) of HfO2 on the MoS2 surface. In contrast to previous reports of conformal growth on MoS2 flakes, we find that ALD on MoS2 bulk material is not uniform. No covalent bonding between the HfO2 and MoS2 is detected. We highlight that individual precursors do not permanently adsorb on the clean MoS2 surface but that organic and solvent residues can dramatically change ALD nucleation behavior. We then posit that prior reports of conformal ALD deposition on MoS2 flakes that had been exposed to such organics and solvents likely rely on contamination-mediated nucleation. These results highlight that surface functionalization will be required before controllable and low defect density high-κ/MoS2 interfaces will be realized. The band structure of the HfO2/MoS2 system is experimentally derived with valence and conduction band offsets found to be 2.67 and 2.09 eV, respectively.
authors.affiliation: Department of Materials Science and Engineering, University of Texas at Dallas , Richardson, Texas 75080, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: McDonnell
authors.forename: Barry
authors.initials: B
authors.lastname: Brennan
authors.forename: Angelica
authors.initials: A
authors.lastname: Azcatl
authors.forename: Ning
authors.initials: N
authors.lastname: Lu
authors.forename: Hong
authors.initials: H
authors.lastname: Dong
authors.forename: Creighton
authors.initials: C
authors.lastname: Buie
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Kim
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Hinkle
authors.forename: Moon J
authors.initials: MJ
authors.lastname: Kim
authors.forename: Robert M
authors.initials: RM
authors.lastname: Wallace