Characterization of Monolayer Transition Metal Dichalcogenides Obtained by Metal Deposition Assisted Mechanical Exfoliation

Transition metal dichalcogenides (TMDs) are atomically thin two-dimensional semiconductors that exhibit rich optoelectronic phenomena, making them strong candidates for next-generation semiconductor devices. Many prototypical devices have been demonstrated in van der Waals heterostructures of various TMDs. However, the scalability of these devices and the ability to study their properties is severely limited by the small size of atomically thin monolayers of TMDs obtained using standard mechanical exfoliation (~ 4 by 4 µm). Recently, gold deposition assisted exfoliation has been demonstrated for obtaining large TMD monolayers (~ 100 by 100 µm) from bulk crystals¹. Here we report the optoelectronic characterization of TMD monolayers obtained using gold deposition assisted exfoliation. We report key optoelectronic figures of merit of these samples that are relevant to both fundamental research and device applications, such as Hall mobility, Raman spectroscopy and low-temperature photoluminescence (T = 4 K). We will also discuss several modifications to the gold-mediated exfoliation technique and their impact on these figures of merit.

S. B. Desai et al., “Gold mediated exfoliation of ultra-large optoelectronically perfect monolayers”, Advanced Materials, 28, 4053-4058, 2016.