Band offsets and heterostructures of two-dimensional semiconductors

摘要

The band offsets and heterostructures of monolayer and few-layer transition-metal dichalcogenides MX_2 (M = Mo, W; X = S, Se, Te) are investigated from first principles calculations. The band alignments between different MX_2 monolayers are calculated using the vacuum level as reference, and a simple model is proposed to explain the observed chemical trends. Some of the monolayers and their heterostructures show band alignments suitable for potential applications in spontaneous water splitting, photovoltaics, and optoelectronics. The strong dependence of the band offset on the number of layers also implicates a possible way of patterning quantum structures with thickness engineering.