Enhanced Terahertz Transmission in Molybdenum Disulfide/Silicon Heterojunction

Recent advances of terahertz (THz) science and technology are witnessing the rapid development of disruptive applications in THz wireless communication and radars, intelligent sensing, and imaging among others. However, the lack of sufficiently multifunctional devices, such as THz modulators, is impeding the proliferation of THz applications, expecting breakthroughs in new materials, structures, and phenomena. Herein, for the first time, anomalously enhanced THz transmission phenomenon in vertically standing molybdenum disulfide (MoS2) nanoplates integrated onto silicon (Si) substrates under active tailoring of photoheating and photodoping is reported. The formation of MoS2/Si heterojunction enables a heat‐induced broadband amplitude improvement exceeding 10%, while photodoping reduces the THz absorption by ≈70% in the measurement frequency region of 0.2–2.0 THz. Through systematically discriminating the transmitted and reflected THz responses from MoS2/Si heterojunction and those from Si substrates, the photothermally decreased THz conductivity can be attributed to the scattering effects, while photodoping‐induced enhancement originates from the decreased carrier density. Further verification experiments are implemented on a 100 GHz video imaging system, and the THz transmission spots become brighter under both stimuli. The observations not only enable an impellent understanding of low‐dimensional light–matter interactions but also provide possible routes for developing novel, integrated, multifunctional THz optoelectronic devices. Anomalous terahertz (THz) transmission enhancement phenomenon is observed when integrating molybdenum disulfide (MoS2) onto n‐type silicon (Si) substrates under the excitations of photothermal effect and photocarrier injection. Through systematic experimental investigations and comprehensive analysis, photothermal effect induced THz enhancement is attributed to the decreased conductivity due to the scattering effect, while reduced photocarriers in MoS2/Si heterostructures enable the decreased absorption.