Abstract
Monolayer MoS2 has recently been identified as a promising material for high-performance electronics. However, monolayer MoS2 must be integrated with ultrathin high-κ gate dielectrics in order to realize practical low-power devices. In this letter, we report the chemical vapor deposition (CVD) of monolayer MoS2 directly on 20 nm thick Al2O3 grown by atomic layer deposition (ALD). The quality of the resulting MoS2 is characterized by a comprehensive set of microscopic and spectroscopic techniques. Furthermore, a low-temperature (200 °C) Al2O3 ALD process is developed that maintains dielectric integrity following the high-temperature CVD of MoS2 (800 °C). Field-effect transistors (FETs) derived from these MoS2/Al2O3 stacks show minimal hysteresis with a sub-threshold swing as low as ∼220 mV/decade, threshold voltages of ∼2 V, and current ION/IOFF ratio as high as ∼104, where IOFF is defined as the current at zero gate voltage as is customary for determining power consumption in complementary logic circuits. The system presented here concurrently optimizes multiple low-power electronics figures of merit while providing a transfer-free method of integrating monolayer MoS2 with ultrathin high-κ dielectrics, thus enabling a scalable pathway for enhancement-mode FETs for low-power applications.
| Original language | English (US) |
|---|---|
| Article number | 053101 |
| Journal | Applied Physics Letters |
| Volume | 110 |
| Issue number | 5 |
| DOIs | |
| State | Published - Jan 30 2017 |
Funding
This work was performed under financial assistance award 70NANB14H012 from the U.S. Department of Commerce, National Institute of Standards and Technology, as part of the Center for Hierarchical Materials Design (CHiMaD). H.B. acknowledges support from the NSERC Postgraduate Scholarship-Doctoral Program. V.K.S. acknowledges support from the 2-DARE program (NSF EFRI-1433510). J.J.M. acknowledges support from the National Aeronautics and Space Administration (NASA NSTRF grant NNX12AM44H). G.P.C. acknowledges support from the Materials Research Science and Engineering Center (MRSEC) of Northwestern University (NSF DMR-1121262). I.B. and X.L. acknowledge support from the Office of Naval Research (ONR N00014-14-1-0669). The Raman instrumentation was funded by the Argonne−Northwestern Solar Energy Research (ANSER) Energy Frontier Research Center (DOE DE-SC0001059). This work made use of the EPIC and Keck-II facilities of the NUANCE Center at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois. The XRR measurements were performed at the Northwestern X-ray Diffraction Facility, which is supported by the MRSEC and SHyNE. The authors thank Dr. K.-S. Chen, Dr. J. Wood, Dr. J. Emery, M. Beck, and S. Wells for valuable discussions.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)