Tailoring Semiconductor Lateral Multi-junctions for Giant Photoconductivity Enhancement

Abstract

Semiconductor heterostructures have played a critical role as the enabler for new science and technology. The emergence of transition metal dichalcogenides (TMDs) as atomically thin semiconductors has opened new frontiers in semiconductor heterostructures either by stacking different TMDs to form vertical heterojunctions or by stitching them laterally to form lateral heterojunctions via direct growth. In conventional semiconductor heterostructures, the design of multi-junctions is critical to achieve carrier confinement. Analogously, we report successful synthesis of monolayer WS2/WS2(1-x)Se2x/WS2 multi-junction lateral heterostructure via direct growth by chemical vapor deposition. The grown structures are characterized by Raman, photoluminescence, and annular dark-field scanning transmission electron microscopy to determine its lateral compositional profile. More importantly, using microwave impedance microscopy, we demonstrate that the local photoconductivity in the alloy region can be tailored and enhanced by 2 orders of magnitude over pure WS2. Finite element analysis confirms that this effect is due to the carrier diffusion and confinement into the alloy region. Our work exemplifies the technological potential of atomically thin lateral heterostructures in optoelectronic applications.

15 pages, 3 figures, just accepted by Advanced Materials

References in corpus (12)

• Atomically thin p-n junctions with van der Waals heterointerfaces
• Electrically Tunable Excitonic Light Emitting Diodes based on Monolayer WSe2 p-n Junctions
• Observation of Long-Lived Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructures
• Mixed-Dimensional van der Waals Heterostructures
• Photovoltaic effect in an electrically tunable van der Waals heterojunction
• Electrical Transport Properties of Single-Layer WS2
• Mechanisms of photoconductivity in atomically thin MoS2
• Picosecond photoresponse in van der Waals heterostructures
• Atomically Thin Resonant Tunnel Diodes built from Synthetic van der Waals Heterostructures
• Esaki diodes in van der Waals heterojunctions with broken-gap energy band alignment
• Quasiparticle band-edge energy and band offsets of monolayer of molybdenum and tungsten chalcogenide
• Modeling of a Cantilever-Based Near-Field Scanning Microwave Microscope

Cited by in corpus (4)

• Unveiling Defect-Mediated Carrier Dynamics in Monolayer Semiconductors by Spatiotemporal Microwave Imaging
• Energy-resolved Photoconductivity Mapping in a Monolayer-bilayer WSe2 Lateral Heterostructure
• Optically Coupled Methods for Microwave Impedance Microscopy
• Spatially Resolved Persistent Photoconductivity in MoS${}_2$-WS${}_2$ Lateral Heterostructures