In-plane epitaxial growth of 2D CoSe-WSe2 metal-semiconductor lateral heterostructures with improved WSe2 transistors performance

Abstract

The two-dimensional (2D) in-plane (lateral) heterostructures have attracted increasing interest for potential applications in the atomically thin electronics and optoelectronics. While most studies focus on semiconductor-semiconductor lateral heterostructures with highly similar lattice structures between the constituent components, the synthesis of metal-semiconductor lateral heterostructures is much less explored and usually more challenging due to more distinct lattice structures or chemical properties. Herein, a vapor phase epitaxy growth method of high-quality metal-semiconductor lateral heterostructures between tetragonal CoSe and hexagonal WSe2 is reported. The 2D CoSe can selectively nucleate at the edge of pre-grown WSe2 nanosheets to form CoSe-WSe2 metal-semiconductor lateral heterostructures. Optical microscopy (OM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies reveal distinct contrast across the heterostructure interface. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) studies further confirm the microstructure modulation across the heterostructure interface. The field-effect transistors (FETs) of CoSe-WSe2 lateral heterostructures show satisfactory Ohmic contacts and considerably better FET performance over those with deposited Cr/Au contacts, suggesting the in-plane metal-semiconductor junctions may function as improved contacts for the atomically thin electronics. (Figure presented.).