AVS 64th International Symposium & Exhibition
    2D Materials Focus Topic Wednesday Sessions
       Session 2D+EM+SS+TF-WeM

Paper 2D+EM+SS+TF-WeM1
Chemical Bath Deposition of Phase Selective MoS2 on Templated Surfaces

Wednesday, November 1, 2017, 8:00 am, Room 15

Session: 2D Materials Growth and Fabrication
Presenter: Jenny Hedlund, University of Texas at Dallas
Authors: J.K. Hedlund, University of Texas at Dallas
A.V. Walker, University of Texas at Dallas
Correspondent: Click to Email
Transition metal dichalcogenides (TMDs) have a wide range of physical properties, and consequently have applications in nanoelectronics and biosensors. While TMD materials have been well studied, a simple method for two-dimensional large area thin film deposition of these materials has yet to be achieved. Chemical bath deposition (CBD) is a robust method by which to grow uniform thin films, and offers many advantages over other techniques including low deposition temperatures (≤ 50°C), synthetic flexibility, and it is inexpensive. In this work, CBD is used to deposit large-area ultra-thin molybdenum disulfide (MoS2), a group VI TMD, and the resulting deposits are investigated by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and time-of-flight secondary ion mass spectrometry (TOF SIMS). These TMDs are most commonly found to possess trigonal prismatic crystalline structure (2H phase) and therefore are semiconductors. Although less widely studied, TMDs can also possess octahedral crystallinity to form the 1T phase. The 1T phase exhibits different properties to the 2H phase, and has applications in sensing, metal contacts and catalysis. By using substrates that mimic the TMD crystalline structure for deposition we have shown that MoS2 can be deposited with large-area crystallites observed. SEM images of deposition performed on highly oriented pyrolytic graphite show large area flakes, ~100 µm in diameter. Smooth thin films were also deposited on sapphire, and functionalized self-assembled monolayers (SAMs). XPS results show that Mo 3d and S 2s peaks are present in the expected positions and ratios. We further demonstrate that the deposited MoS2 phase is likely determined by the surface chemistry of the substrate. Using Raman spectroscopy measurements, the thickness and phase of the film are elucidated. CBD of MoS2 was further characterized using TOF SIMS to elucidate the reaction mechanisms as well as the stability of the deposited film.