Study On Photoelectric Properties Of Two-dimensional Semiconductors And Their Heterostructures Tuned By Ferroelectrics

With the development of semiconductor technology,traditional semiconductor materials and devices are facing new challenges.In recent years,the rise of two-dimensional materials has provided new opportunities for the development of semiconductor routes.In two-dimensional materials and their heterostructures,many novel physical effects have been discovered,new device structures have been constructed and many new application fields have been explored.These new low-dimensional materials and structures have opened up new technological approaches for the development of nano-optoelectronic devices.In the field of optoelectronic devices,semiconductor heterojunctions,field effect transistors and other structures are the basic building blocks in semiconductor chips,and their characteristic performance parameters are important indicators for measuring semiconductor technology.This thesis mainly studies the electrical and optoelectronic properties of two-dimensional semiconductors and their heterostructures tuned by organic ferroelectric materials.The potential applications in photodetectors and low-power electronic devices were also explored.The main content has the following aspects:1.We studied the photoelectric properties of the N-type MoS₂ FET and the P-type WSe₂ FET gated by the relaxation ferroelectric polymer material P?VFE-TrFE-CFE?.Intrinsic physical mechanisms for enhancing electron and hole mobility by P?VDF-TrFE-CFE?were analyzed respectively.MoS₂ photodetectors regulated by ferroelectric were constructed and the photoelectric properties were investigated.The photodetector achieved high responsivity from visible to near-infrared range.The detection range of MoS₂ was broden and the mechanism of the bandgap modulation by ferroelectric localized field is revealed.2.Van der Waals heterostructure PN junction based on two-dimensional MoTe₂and MoS₂ was fabricated.The photodetection performance of the heterostructure was studied.The device exhibted typical photovoltaic effect characteristics,and realized high sensitivity and fast detection function without driving voltage.The dark current is extremely low and signal-to-noise ratio are very high.We further analyzed the carrier transport,photo-induced carrier generation and recombination process under different bias voltages.This heterostructure device based on low-dimensional materials can be used as visible-near-infrared photodetectors with low-power consumption and high-performance.3.The photoelectric properties and band structure of GeSe/MoS₂ van der Waals PN junction tuned by ferroelectric polymer P?VDF-TrFE?were measured and analyzed.The anisotropic GeSe makes the PN junction a photovoltaic detector sensitive to polarization light.The heterojunction energy band structure changed from staggered gap?type II?to straddling gap?type I?under the modulation of ferroelectric field of P?VDF-TrFE?.It is confirmed that the ferroelectric local field not only expands the detection range of two-diemsional detectors,but also significantly enhances the polarization detection ratio.Such polarization-sensitive photodetectors are important components in the application fields of space remote sensing and bionic detection.4.SnSe₂/MoTe₂ tunneling field effect transistors with HfO₂ backgate or P?VDF-TrFE?topgate are investigated respectively.It is found that the localized ferroelectric polarization field shows a stronger ability to regulate the SnSe₂/MoTe₂PN junction,and the heterojunction exhibited quantum tunneling effect.When the ferroelectric material is polarized up,a significant negative differential resistance phenomenon was observed.Utilizing the stable polarization retention characteristics of ferroelectrics,the tunneling devices will have strong application potential in the field of ultra-low power consumption electronic and optoelectronic devices in the future.