MoS2-Titanium Contact Interface Reactions

The formation of the Ti-MoS2 interface, which is heavily utilized in nanoelectronic device research, is studied by X-ray photoelectron spectroscopy. It is found that, if deposition under high vacuum (similar to 1 X 10(-6) mbar) as opposed to ultrahigh vacuum (similar to X 10(-)9 mbar) conditions are used, TiO2 forms at the interface rather than Ti. The high vacuum deposition results in an interface free of any detectable reaction between the semiconductor and the deposited contact. In contrast, when metallic titanium is successfully deposited by carrying out depositions in ultrahigh vacuum, the titanium reacts with MoS2 forming TixSy and metallic Mo at the interface. These results have far reaching implications as many prior studies assuming Ti contacts may have actually used TiO2 due to the nature of the deposition tools used.