Light-triggered interfacial charge transfer and enhanced photodetection in CdSe/ZnS quantum dots/MoS_(2)mixed-dimensional phototransistors

Mix-dimensional van der Waals heterostructures(vdWHs)have inspired worldwide interests and efforts in the field of ad-vanced electronics and optoelectronics.The fundamental understanding of interfacial charge transfer is of vital import-ance for guiding the design of functional optoelectronic applications.In this work,type-Ⅱ0D-2D CdSe/ZnS quantum dots/MoS_(2)vdWHs are designed to study the light-triggered interfacial charge behaviors and enhanced optoelectronic performances.From spectral measurements in both steady and transient states,the phenomena of suppressed photolu-minescence(PL)emissions,shifted Raman signals and changed PL lifetimes provide strong evidences of efficient charge transfer at the 0D-2D interface.A series of spectral evolutions of heterostructures with various QDs overlapping concentrations at different laser powers are analyzed in details,which clarifies the dynamic competition between exciton and trion during an efficient doping of 3.9×10^(13)cm^(−2).The enhanced photoresponses(1.57×10^(4)A·W^(-1))and detectivities(2.86×10^(11)Jones)in 0D/2D phototransistors further demonstrate that the light-induced charge transfer is still a feasible way to optimize the performance of optoelectronic devices.These results are expected to inspire the basic understand-ing of interfacial physics at 0D/2D interfaces,and shed the light on promoting the development of mixed-dimensional op-toelectronic devices in the near future.

High-performance optoelectronic devices based on van der Waals vertical MoS2/MoSe2 heterostructures

Monolayer MoS2 is a direct band gap semiconductor with large exciton binding energy,which is a promising candidate for the application of ultrathin optoelectronic devices.However,the optoelectronic performance of monolayer M0S2 is seriously limited to its growth quality and carrier mobility.In this work,we report the direct vapor growth and the optoelectronic device of verticallystacked MoS2/MoSe2 heterostructure,and further discuss the mechanism of improved device performance.The optical and high-resolution atomic characterizations demonstrate that the heterostructure interface is of high-quality without atomic alloying.Electrical transport measurements indicate that the heterostructure transistor exhibits a high mobility of 28.5 cm^2/(V·s)and a high on/off ratio of 10^7.The optoelectronic characterizations prove that the heterostructure device presents an enhanced photoresponsivity of 36 A/W and a remarkable detectivity of 4.8×10^11 Jones,which benefited from the interface induced built-in electric field and carrier dependent Coulomb screening effect.This work demonstrates that the construction of two-dimensional(2D)semiconductor heterostructures plays a significant role in modifying the optoelectronic device properties of 2D materials.

Plasmonically engineered light-matter interactions in Aunanoparticle/MoS_(2) heterostructures for artificial optoelectronic synapse

Optoelectronic synaptic elements are emerging functional devices for the vigorous development of advanced neuromorphic computing technology in the post-Moore era.However,optoelectronic devices based on transition metal dichalcogenides(TMDs)are limited to their poor mobilities and weak light-matter interactions,which still hardly exhibit superior device performances in the application of artificial synapses.Here,we demonstrate the successful fabrication of Au nanoparticle-coupled MoS_(2)heterostructures via chemical vapor deposition(CVD),where the light absorption of MoS_(2)is greatly enhanced and engineered by plasmonic effects.Hot electrons are excited from Au nanoparticles,and then injected into MoS_(2)semiconductors under the light illumination.The plasmonically-engineered photo-gating effect at the metal-semiconductor junction is demonstrated to create optoelectronic devices with excellent synaptic behaviors,especially in ultra-sensitive excitatory postsynaptic current(EPSC,9.6×10^(-3)nA@3.4 nW·cm^(-2)),ultralow energy consumption(34.7 pJ),long-state retention time(>1,000 s),and tunable synaptic plasticity transitions.The material system of Au-nanoparticles coupled TMDs presents unique advantages for building artificial synapses,which may lead the future development of neuromorphic electronics in optical information sensing and learning.