Lateral heterojunctions within monolayer MoSe2–WSe2 semiconductors

Abstract

Heterojunctions between three-dimensional (3D) semiconductors with different bandgaps are the basis of modern light-emitting diodes, diode lasers and high-speed transistors. Creating analogous heterojunctions between different 2D semiconductors would enable band engineering within the 2D plane and open up new realms in materials science, device physics and engineering. Here we demonstrate that seamless high-quality in-plane heterojunctions can be grown between the 2D monolayer semiconductors MoSe2 and WSe2. The junctions, grown by lateral heteroepitaxy using physical vapour transport, are visible in an optical microscope and show enhanced photoluminescence. Atomically resolved transmission electron microscopy reveals that their structure is an undistorted honeycomb lattice in which substitution of one transition metal by another occurs across the interface. The growth of such lateral junctions will allow new device functionalities, such as in-plane transistors and diodes, to be integrated within a single atomically thin layer.

Electronic and Optoelectronic Applications Based on 2D Novel Anisotropic Transition Metal Dichalcogenides

“…CVD is a well‐established technology that has been demonstrated as a facile method for synthesizing large‐scale monolayer crystals, including graphene, MX 2 ,73, 110, 126, 127, 128, 129, 130, 131, 132, 133, 134 and their heterojunctions 135, 136, 137, 138, 139, 140. Compared with the exfoliation method, the direct synthesis of few‐layer and monolayer MX 2 by CVD is critical to large‐scale applications.…”

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…Van der Waals (vdW) heterostructures composed of 2D layered materials have been attempted intensively recently due to the novel physical properties covering a wide range of electronic, optical, and optoelectronic systems 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242. Jo and co‐workers130 synthesized polymorphic 2D tin‐sulfides of either p‐type SnS or n‐type SnS 2 via adjusting hydrogen during the process.…”

Nanoscale interfaces made easily

“…Lateral TMD heterostructures can be constructed by 'stitching' the edges of two TMD sheets together using covalent bonds. In the past few years, there has been a flurry of papers [5][6][7][8][9] reporting methods for synthesizing TMD lateral heterostructures using edge epitaxial growth, a method that allows a second TMD to grow at the edge of another, pre-grown TMD crystal. These heterostructures can be fabricated into p-n junctions, which conduct currents in only one direction (a property known as rectification), and constitute one of the building blocks of modern electronic and optoelectronic devices.…”

“…Lateral TMD heterostructures have previously been made in one-step procedures 5,6 that lacked the flexibility to make multi-junction heterostructures or more than one type of heterostructure, or in two-step or multi-step processes that involve many changes of TMD precursors and reaction chambers [7][8][9] . Sahoo and colleagues' method overcomes those constraints in a 'one-pot' procedure -a process that allows several steps to be performed in one reaction chamber.…”

“…First, the authors added physiological concentrations of fibrinogen to OPCs in cell culture, and showed that this coagulation factor strongly inhibited OPC differentiation and prevented axon myelination. Among the many genes in OPCs whose expression was affected by fibrinogen, the researchers detected upregulation of members of a signalling pathway known to inhibit oligodendrocyte differentiation 6 -genes encoding bone morphogenetic proteins (BMPs) and their downstream effectors, including the transcription factor ID2. Indeed, Petersen and colleagues showed that fibrinogen and ID2 could be readily visualized in regions in which remyelination had failed in the brains of people who had died with MS.…”