Thermal Stability of Titanium Contacts to MoS<sub>2</sub>
Published on 2019-09-11T18:34:52Z (GMT) by
Thermal annealing of Ti contacts is commonly implemented in the fabrication of MoS<sub>2</sub> devices; however, its effects on interface chemistry have not been previously reported in the literature. In this work, the thermal stability of titanium contacts deposited on geological bulk single crystals of MoS<sub>2</sub> in ultrahigh vacuum (UHV) is investigated with X-ray photoelectron spectroscopy and scanning transmission electron microscopy (STEM). In the as-deposited condition, the reaction of Ti with MoS<sub>2</sub> is observed resulting in a diffuse interface between the two materials that comprises metallic molybdenum and titanium sulfide compounds. Annealing Ti/MoS<sub>2</sub> sequentially at 100, 300, and 600 °C for 30 min in UHV results in a gradual increase in the reaction products as measured by XPS. Accordingly, STEM reveals the formation of a new ordered phase and a Mo-rich layer at the interface following heating. Due to the high degree of reactivity, the Ti/MoS<sub>2</sub> interface is not thermally stable even at a transistor operating temperature of 100 °C, while post-deposition annealing further enhances the interfacial reactions. These findings have important consequences for electrical transport properties, highlighting the importance of interface chemistry in the metal contact design and fabrication.
Cite this collection
Freedy, Keren M.; Zhang, Huairuo; Litwin, Peter M.; Bendersky, Leonid A.; Davydov, Albert V.; McDonnell, Stephen (2019): Thermal
Stability of Titanium Contacts to MoS2. ACS Publications. Collection. https://doi.org/10.1021/acsami.9b08829