Research On Photosensitive Field Effect Transistor And Photodiode Of Multilayer MoS₂

Molybdenum disulfide（MoS₂）,a two-dimensional transition metal sulfide,has attracted extensive attention because of its excellent optical and electrical properties.Compared with single-layer MoS₂,multilayer MoS₂ can achieve stronger light absorption.Therefore,photosensitive field effect transistor（FET）and photodiode have better development prospects.This work focuses on the research of multilayer MoS₂photodetector,and has achieved innovative results.Multilayer MoS₂ photosensitive field effect transistors with silica（SiO₂）and polymethylmethacrylate（PMMA）as insulating gate dielectric was compared and studied.The results show that the SiO₂ gate dielectric device presents the characteristics of continuous n-type field effect photoconductivity,which is the conductivity of the device unable return to the state before illumination.Compared with the conductivity under illumination,it is only slightly reduced,and the normal light detection function cannot be realized.PMMA gate dielectric devices exhibit normal bipolar field effect photoconductivity.When the gate voltage was-50 V,the drain voltage was-10 V and the incident optical intensity at 650 nm was 0.03 m W/cm²,the light response reached581.89 A/W.The temperature characteristics of the device were studied.The results showed that the dark current increased with the increase of temperature in the temperature range of 243～343 K.The effect of PMMA film modified SiO₂ surface on its multilayer MoS₂photosensitive FET was studied.The results show that spin coating dozens of nano PMMA films on the surface of SiO₂ could effectively eliminate the continuous photocurrent effect of SiO₂ gate dielectric devices and realized the normal optical detection function.When the gate voltage was 0 V,the drain voltage was 10 V,the incident optical intensity was 0.03 m W/cm² and the wavelength was 650 nm,the device D had the maximum light response of 24.24 A/W.A photodiode with"ITO/multilayer MoS₂/Au"structure was fabricated.the photodiode with a bias voltage of 3 V,an incident optical intensity of 0.03 m W/cm²and the wavelength of 650 nm,it had a maximum light response of 536.2 A/W,a specific detection rate of 5.27×10¹⁰ Jones,and external quantum efficiency of1024.68%.Much higher than conventional silicon photodiode.A photodiode based on MoS₂/Cu Pc heterojunction was studied,with a maximum light response of 4847 A/W at bias voltage of 3 V and incident optical intensity of 0.03 m W/cm² and the wavelength of 650 nm,a specific detection rate of 1.10×10¹² Jones,and external quantum efficiency of 9,262.62%.Compared with multilayer MoS₂ device,it was 8.04 times,19.87 times,and 8.04 times higher.