| AVS 62nd International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS+2D+SE-WeM |
| Session: | Plasma Diagnostics, Sensors and Control II |
| Presenter: | Angelica Azcatl, The University of Texas at Dallas |
| Authors: | A. Azcatl, The University of Texas at Dallas X. Qin, The University of Texas at Dallas Q. Wang, The University of Texas at Dallas N. Lu, The University of Texas at Dallas M.J. Kim, The University of Texas at Dallas C.L. Hinkle, The University of Texas at Dallas R.M. Wallace, The University of Texas at Dallas |
| Correspondent: | Click to Email |
Two-dimensional molybdenum disulfide (MoS2) is currently considered as a potential channel material for CMOS applications. Electron mobilities on the order of 470 cm2/Vs [1] have been reported for few-layer MoS2 based FETs. Such promising results have fueled the efforts on synthesis of large area and high quality mono and few-layer MoS2. Yet, the development of MoS2 processing techniques of interest for device fabrication (i.e. doping, etching, functionalization) is still in an early stage.
Recently, it has been reported that when MoS2 is exposed to SF6, CF4 or CHF3 plasma treatments, fluorine can be introduced in the MoS2 structure as an acceptor dopant, resulting in p-type doping. In parallel, due to the weak van der Waals interlayer forces, layer etching occurred as a side effect after these fluorine-based plasma exposures. [2]
Following the exploration of the effect of plasma exposures on MoS2, in this study nitrogen plasma exposures on MoS2 were performed, while the surface chemistry was monitored by in-situ by X-ray Photoelectron Spectroscopy. Theoretical studies have shown that substitution of sulfur with nitrogen in MoS2 leads to p-type doping. [3,4] Here, the chemical analysis obtained by XPS indicates that nitrogen will covalently interact with molybdenum to generate molybdenum nitride. It was found that the nitrogen content in MoS2 can be controlled with exposure time. The thermal stability of MoNx formed due to sulfur replacement with nitrogen will be discussed. Finally, Raman Spectroscopy studies and Scanning Transmission Electrons Microscopy imaging on the MoNx/MoS2 structure will be presented to discuss the impact of the Mo-N bonding environment on the MoS2 structure. This study will give an important insight for the understanding of the interaction of MoS2 with a non-metal dopant atom, nitrogen, which has implications on the electrical properties of MoS2.
This work is supported in part 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, and by the SWAN Center, a SRC center sponsored by the Nanoelectronics Research Initiative and NIST.
References
[1] W. Bao, et al. Applied Physics Letters 102, 042104 (2013).
[2] M. Chen, et al., Appl. Phys. Lett. 103, 142110 (2013).
[3] H.-P. Komsa, et al., Phys. Rev. B 88, 035301 (2013).
[4] Q. Yue, et al., Phys. Lett. A 377, 1362 (2013).