| AVS 63rd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Wednesday Sessions |
| Session 2D+TF-WeM |
| Session: | 2D Materials: Growth and Fabrication |
| Presenter: | Berc Kalanyan, National Institute of Standards and Technology (NIST) |
| Authors: | B. Kalanyan, National Institute of Standards and Technology (NIST) J.E. Maslar, National Institute of Standards and Technology (NIST) W.A. Kimes, National Institute of Standards and Technology (NIST) B.A. Sperling, National Institute of Standards and Technology (NIST) E. Garratt, National Institute of Standards and Technology (NIST) B. Nikoobakht, National Institute of Standards and Technology (NIST) R. Beams, National Institute of Standards and Technology (NIST) S.J. Stranick, National Institute of Standards and Technology (NIST) A.V. Davydov, National Institute of Standards and Technology (NIST) |
| Correspondent: | Click to Email |
Layered two dimensional (2D) transition-metal dichalcogenides (TMDs), e.g., MoS2, are of increasing interest for next-generation nanoelectronic and optoelectronic devices due to their thickness dependent optical and electrical properties. For many applications, high volume manufacturing of devices based on TMDs will require deposition techniques that are capable of reproducibly growing wafer-scale films with monolayer control. To date, TMD deposition processes largely rely on powder vaporization and transport, with minimal control over precursor fluxes and chemistry. A detailed understanding of metal and chalcogen precursor chemistry in relation to film properties remains an important step toward the design of highly-controllable deposition processes suitable for large-scale 2D synthesis.
We aim to identify promising chemistries for chemical vapor deposition (CVD) processes for TMDs. We focus on MoS2 CVD using organometallic and organosulfur compounds in a research grade single-wafer deposition system equipped with in situ optical diagnostics. The precursor flux is measured using optical mass flow meters installed on the delivery lines while deposition chemistry is characterized in the reactor volume above the deposition surface using in situ Fourier transform infrared (FTIR) spectroscopy. As-deposited and annealed films are characterized with ex situ techniques, including Raman and photoluminescence spectroscopy, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy.
Large-area thin films of MoS2 were prepared from (η5-ethylcyclopentadienyl)-dicarbonylnitrosyl molybdenum, cycloheptatriene tricarbonyl molybdenum, bis(ethylbenzene) molybdenum, 1-propane thiol, and diethyl disulfide sources. Film composition and growth rates on SiO2 and c-plane Al2O3 were characterized for each compound as a function of precursor exposure time. Gas phase reaction chemistry and thermal stability of precursors were evaluated using FTIR spectroscopy. The full-width at half-maximum values for in-plane (E2g1) and out-of-plane (A1g) Raman modes for MoS2 were used as indicators of film quality. By relating film properties to gas-phase chemistry for various metal precursors, we will highlight precursor design and process conditions that lead to high quality CVD films.