The Impact of Semimetallic Bismuth Electrical Contacts on Optical Properties of a MoS2 Monolayer

Abstract Achieving high performance in transition-metal dichalcogenide-based optoelectronic devices is challenging because the realization of an efficient electrical contacting scheme should not be obtained at the expense of their optical quality. Here, we present the results of optical studies of MoS2 monolayers that have been electrically contacted with bismuth and gold. The photoluminescence (PL) spectra of the samples contacted with both materials are significantly broadened. In the case of the bismuth-contacted sample, we observe an additional low-energy band in the PL spectrum, which we attribute to a defect state formed during the evaporation of Bi. Comparison of the intensities of the excitonic peak and the defect-related peak reveals that there is a correlation between the type of contacts and the optical properties of the contacted material.