A Waveguide-Integrated Two-Dimensional Light-Emitting Diode Based on p-Type WSe₂/n-Type CdS Nanoribbon Heterojunction

Abstract

Transition metal dichalcogenides (TMDs) have emerged as two-dimensional (2D) building blocks to construct nanoscale light sources. To date, a wide array of TMD-based light-emitting devices (LEDs) have been successfully demonstrated. Yet, their atomically thin and planar nature entails an additional waveguide/microcavity for effective optical routing/confinement. In this sense, integration of TMDs with electronically active photonic nanostructures to form a functional heterojunction is of crucial importance for 2D optoelectronic chips with reduced footprint and higher integration capacity. Here, we report a room-temperature waveguide-integrated light-emitting device based on a p-type monolayer (ML) tungsten diselenide (WSe2) and n-type cadmium sulfide (CdS) nanoribbon (NR) heterojunction diode. The hybrid LED exhibited clear rectification under forward biasing, giving pronounced electroluminescence (EL) at 1.65 eV from exciton resonances in ML WSe2. The integrated EL intensity against the driving current shows a superlinear profile at a high current level, implying a facilitated carrier injection via intervalley scattering. By leveraging CdS NR waveguides, the WSe2 EL can be efficiently coupled and further routed for potential optical interconnect functionalities. Our results manifest the waveguided LEDs as a dual-role module for TMD-based optoelectronic circuitries.

WSe2 Light-Emitting Device Coupled to an h-BN Waveguide

“…The co-integration of light-emitting devices (LEDs) with on-chip photonics has been demonstrated, ,,, for example by placing 2D materials on top of silicon-based waveguides to couple their emission via evanescent fields . However, placing the active material inside the light-confining dielectric, where the field intensity is higher, improves the mode overlap between the emitter and waveguide mode, − and thereby the coupling efficiency .…”

“…With the rapid advances in the field of optical information processing, the demand for the development of integrated photonic circuits is constantly increasing. Along with photodetectors and optical modulators, a fundamental building block is integrated light sources, which have, however, remained a challenge and led to extensive research. − One suitable material class that has shown great potential for integrated optoelectronic devices is two-dimensional (2D) materials. − Among others, one benefit is the vertical assembly of dissimilar 2D materials to form van der Waals (vdW) heterostructures, which can be placed on almost any substrate without constraints of lattice matching . The resulting possibility of band structure engineering with atomic precision has opened up a new level of control for the design of light-emitting quantum wells, − tunnel junctions, and other optoelectronic devices. − …”

Defect-Mediated Electron Transfer in Pt-CuInS2/CdS Heterostructured Nanocrystals for Enhanced Photocatalytic H2 Evolution

“…Particularly, the band gap of cadmium sulfide (CdS) is about 2.4 eV, which can effectively absorb the visible part of solar light. Furthermore, the applicability of its conduction band for water splitting to hydrogen shows excellent photocatalytic activity . In addition, platinum (Pt) was considered as an ideal cocatalyst, which can provide lots of active centers, reduce the overpotential of HER, and improve the separation efficiency of photogenerated carriers .…”

“…Furthermore, the applicability of its conduction band for water splitting to hydrogen shows excellent photocatalytic activity. 39 In addition, platinum (Pt) was considered as an ideal cocatalyst, which can provide lots of active centers, reduce the overpotential of HER, and improve the separation efficiency of photogenerated carriers. 40 Although these methods could favor high photocatalytic activity, the relative importance of each factor in the formation of the semiconducting heterojunction and the modification of the cocatalyst in one NC for photocatalytic hydrogen evolution under visible light irradiation are unclear.…”

On-Chip Ultralow-Threshold Tunable CdSSe Nanobelt Lasers Excited by the Emission of Linked ZnO Nanowire

“…Thus, the lasing threshold is high, and a large amount of heat is generated. Under this condition, the lasing occurrence needs much more phonons to facilitate exciton recombination. ,− …”