Polarization-Resolved Photodetectors Based On Layered Materials

Polarization reflects the vector property of light.The polarization states of light provide an extra degree of freedom to carry the information and thus it is important to explore efficient ways to detect the ploarzaiton states of light.However,currently the on-chip polarization detectors usually rely on three-dimensional(3D)material heterojunction,and the growth of each layer must consider the influence of lattice matching.These will increase the difficulty to prepare the detector with a high integration density.Therefore,it is very important to explore new polarization materials and detector structures.Layered materials are a new type of semiconductors that the interaction among layers is weak van der Waals force.Such materials not only present a higher degree of integration than3D materials,but also need not consider the influence of lattice matching in the preparation of heterojunctions.Among the layered materials,two-dimensional(2D)perovskites and transitional metal dichalcogenides have the detection capability of both linear polarized light and circular polarized light,therefore they are especially suitable for developing polarization detectors.In this dissertation,we focus on the synthesis,property and device structure of 2D perovskites and transitional metal dichalcogenides in the polarization detection,and fabricate new-type polarization photodetectors based on them.Specific contents include:1.We developed a low-toxicity and heat-free aqueous method to synthesize low-dimensional perovskite crystals.The X-ray diffraction,photoluminescence and circular dichroism measurements prove the universality and high yield of this synthesis method.2.A high-performance photodetector based on 2D perovskite heterojunctions was successfully demonstrated.We stacked the lead-free 2D perovskite(PEA)₂SnI₄(PEA=?- phenyethylamine)with few-layer MoS₂and graphene to form a heterojunction,and thus the photodetection ability of the perovskite is greatly enhanced with a high responsivity of 1100 A/W and an external quantum efficiency of up to 33.3%under zero bias.3.The polarization detection has been realized based on 2D perovskite photodetectors.For linear polarization detection,we made a comprehensive study on the polarization optical properties based on a new-type 2D perovskite FAGPb I₄(FA=formidine,G=guanidine) by means of theoretical calculation and experimental analysis,and verified the excellent linear polarization luminescence and detection ability of the perovskite on each crystal plane. Besides,the magnitude and polarization direction of anisotropy can be regulated by changing the temperature.For circular polarization detection,we studied the chiral perovskites synthesized by the aqueous method and fabricated high-performance circular polarization detectors based on them.4.A filterless on-chip full-Stokes polarimeter based on layered materials has been demonstrated with decent performance.By combining the single-layer MoS₂ with few-layer MoS₂ to form a homojunction,the circular photogalvanic effect(CPGE)under low excitation power and zero bias is greatly enhanced thanks to the built-in electric field. Afterwards,we successfully demonstrated a filterless on-chip full-Stokes polarimeter based on the single-layer MoS₂/few-layer MoS₂homojunction.The device can operate under self-powered condition with the minimum errors of 5%,4.8%and 6.7%for parameters S₁,S₂ and S₃,respectively.