Repairing atomic vacancies in single-layer MoSe2 field-effect transistor and its defect dynamics

Abstract

Atomic defects are easily created in the single-layer electronic devices of current interest and cause even more severe influence than in the bulk devices since the electronic quantum paths are obviously suppressed in the two-dimensional transport. Here we find a drop of chemical solution can repair the defects in the single-layer MoSe2 field-effect transistors. The devices' room-temperature electronic mobility increases from 0.1 cm2/Vs to around 30 cm2/Vs and hole mobility over 10 cm2/Vs after the solution processing. The defect dynamics is interpreted by the combined study of the first-principles calculations, aberration-corrected transmission electron microscopy, and Raman spectroscopy. Rich single/double Selenium vacancies are identified by the high-resolution microscopy, which cause some mid-gap impurity states and localize the device carriers. They are found to be repaired by the processing with the result of extended electronic states. Such a picture is confirmed by a 1.5 cm-1 red shift in the Raman spectra.