Modulation of electrical properties in MoTe by XeF-mediated surface oxidation.

Transition metal dichalcogenides (TMDs) are promising candidates for the semiconductor industry owing to their superior electrical properties. Their surface oxidation is of interest because their electrical properties can be easily modulated by an oxidized layer on top of them. Here, we demonstrate the XeF-mediated surface oxidation of 2H-MoTe (alpha phase MoTe). MoTe exposed to XeF gas forms a thin and uniform oxidized layer (∼2.5 nm-thick MoO ) on MoTe regardless of the exposure time (within ∼120 s) due to the passivation effect and simultaneous etching. We used the oxidized layer for contacts between the metal and MoTe, which help reduce the contact resistance by overcoming the Fermi level pinning effect by the direct metal deposition process. The MoTe field-effect transistors (FETs) with a MoO interlayer exhibited two orders of magnitude higher field-effect hole mobility of 6.31 cm V s with a high on/off current ratio of ∼10 than that of the MoTe device with conventional metal contacts (0.07 cm V s). Our work shows a straightforward and effective method for forming a thin oxide layer for MoTe devices, applicable for 2D electronics.