| AVS 60th International Symposium and Exhibition | |
| Graphene and Other 2D Materials Focus Topic | Thursday Sessions |
| Session GR+EM+NS+SS+TF-ThA |
| Session: | Beyond Graphene: Other 2D Electronic Materials and their Heterostructures |
| Presenter: | S. McDonnell, University of Texas at Dallas |
| Authors: | S. McDonnell, University of Texas at Dallas A. Azcatl, University of Texas at Dallas C. Buie, University of Texas at Dallas N. Lu, University of Texas at Dallas J. Kim, University of Texas at Dallas C.L. Hinkle, University of Texas at Dallas M.J. Kim, University of Texas at Dallas R.M. Wallace, University of Texas at Dallas |
| Correspondent: | Click to Email |
The transition metal dichalcogenide (TMD) family of materials are 2-D bulk crystals similar to graphite that can be exfoliated to yield single-layer analogs to graphene. The materials can be metallic or semiconducting with bandgaps that are tunable with thickness. Recent publications have focused on devices fabricated with MoS2 or WSe2 channels and the deposition of thick gate oxides was carried out by atomic layer deposition (ALD) without any functionalization suggesting that these surfaces may be more reactive than graphene.1,2
Preliminary results have shown that the direct deposition of HfO2 using tetrakis (dimethylamino) hafnium (TDMA-Hf) and H2O precursors on MoS2 is not a scalable process. The deposition of films less than 15 nm in thickness is three-dimensional, with pinholes reaching the MoS2 surface. Ozone functionalization of graphene, as well as the deposition of seed layers by e-beam, has been previously shown to allow the subsequent uniform growth of high-k materials by ALD.3,4
Presented here will be a comparative study of ozone and e-beam seed-layer based functionalization. X-ray photoelectron spectroscopy will be used to probe the interfaces for any chemical reactions. Atomic force microscopy, inelastic ion scattering, and transmission electron microscopy will be used to monitor the film uniformity. The band offsets of the resultant heterostructures will also be presented.
This work was supported in part by the Center for Low Energy Systems Technology (LEAST), one of six centers supported by the STARnet phase of the Focus Center Research Program (FCRP), a Semiconductor Research Corporation program sponsored by MARCO and DARPA. C. L. Hinkle acknowledges support from the Nanoelectronic Research Initiative (NRI SWAN Center).
1 B. Radisavljevic et al., "Single-layer MoS2 transistors," Nature nanotechnology 6 (3), 147-150 (2011).
2 H. Fang et al., "High-Performance Single Layered WSe2 p-FETs with Chemically Doped Contacts," Nano letters 12 (7), 3788-3792 (2012).
3 B. Lee et al., "Characteristics of high-k Al2O3 dielectric using ozone-based atomic layer deposition for dual-gated graphene devices," Applied Physics Letters 97, 043107 (2010).
4 B. Fallahazad et al., "Dielectric thickness dependence of carrier mobility in graphene with HfO2 top dielectric," Applied Physics Letters, 97, 123105 (2010).