Understanding the impact of annealing on interface and border traps in the Cr/HfO2/Al2O3/MoS2 system
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Date
2019-06-24
Authors
Zhao, Peng
Padovani, Andrea
Bolshakov, Pavel
Khosravi, Ava
Larcher, Luca
Hurley, Paul K.
Hinkle, Christopher L.
Wallace, Robert M.
Young, Chadwin D.
Journal Title
Journal ISSN
Volume Title
Publisher
American Chemical Society (ACS)
Published Version
Abstract
Top-gated, few-layer MoS2 transistors with HfO2 (6 nm)/Al2O3 (3 nm) gate dielectric stacks are fabricated and electrically characterized by capacitance–voltage (C–V) measurements to study electrically active traps (Dit) in the vicinity of the Al2O3/MoS2 interface. Devices with low Dit and high Dit are both observed in C–V characterization, and the impact of H2/N2 forming gas annealing at 300 and 400 °C on the Dit density and distribution is studied. A 300 °C anneal is able to reduce the Dit significantly, while the 400 °C anneal increases defects in the gate stack. Simulation with modeled defects suggests a sizable decrease in Dit, half the amount of positive fixed charge in the dielectric, and slightly increased unintentional doping in MoS2 after a 300 °C anneal. In the as-fabricated devices displaying high Dit levels, the energy distribution of the Dit located at the Al2O3/MoS2 interface is continuous from the conduction band edge of MoS2 down to 0.13–0.35 eV below the conduction band edge. A plausible Dit origin in our experiments could come from the unexpected oxygen atoms that fill the sulfur vacancies during the UV–O3 functionalization treatment. The border trap concentration in Al2O3 is the same, both before and after the anneal, suggesting a different origin of the border traps, possibly due to the low-temperature atomic-layer-deposited process.
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Keywords
Molybdenum disulfide (MoS2) , High-k dielectrics , Al2O3 , Interface traps , Border traps , Capacitance-voltage (C-V)
Citation
Zhao, P., Padovani, A., Bolshakov, P., Khosravi, A., Larcher, L., Hurley, P. K., Hinkle, C. L., Wallace R. M. and Young, C. D. (2019) 'Understanding the impact of annealing on interface and border traps in the Cr/HfO2/Al2O3/MoS2 system', ACS Applied Electronic Materials, 1 (8), pp.1372-1377. doi: 10.1021/acsaelm.8b00103
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Copyright
© 2019, American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Electronic Materials, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acsaelm.8b00103