Physical Property Of Two-dimenaional Tellurene And Electronic Devices

The rapid development of artificial intelligence（AI）technology necessitates enhanced memory stability,heightened perceptual sensitivity,and increased computational capabilities within hardware frameworks.Current memory,sensors,and processors confront significant obstacles such as diminished memory lifespan,inadequate perception and the presence of a memory wall.These challenges are primarily attributed to issues including material segregation,weak photo-matter coupling,and physical separation between sensor and memory components.These issues hinder the development of microelectronics in meeting the escalating demands of burgeoning AI technologies.As a result,efforts to develop new materials,explore novel physical phenomena,and create innovative device architectures are becoming crucial for achieving microelectronics with high reliability,fast computational speeds,and stable information interaction.Two-dimensional（2D）materials,known for their strong light-matter couplings and dangling-bonds-free property,exhibit numerous distinctive physical properties compared to the bulk state,which is believed to be ideal materials for novel neuromorphic-inspired devices.Tellurene,in particular,stands out with intrinsic symmetry-breaking property and highly oriented molecular structures,as well as unique soft phonon features.Consequently,tellurene is capable to overcome current challenges such as elemental segregation,low detection sensitivity,and slow sensing-memory speed,and achieve constructing high-reliable memory,ultra-sensitive sensor,and ultra-fast sensing-memory all-in-one devices.Nonetheless,the elusive mechanisms underlying spontaneous polarization,the weak localized electric field and lack of photo-carrier relaxation mechanisms collectively pose substantial barriers to its practical deployment in electronic applications.This dissertation focuses on the investigation of spontaneous polarization phenomena,soft-phonon dominated photo-carrier relaxation dynamics,and the establishment of strong localized surface plasmon electric fields in tellurene.It reveals the nature and mechanisms of piezoelectrical spontaneous polarization in tellurene,the effects of soft phonons and defect states on photo-carrier lifetimes,and the actual relationship between plasmonic nanostructures and electric field localization effects.The dissertation achieves the development of segregation-free reliable memory,ultra-fast sensing-memory all-in-one devices at MHz,and single-molecule level optical sensing as well as encryption.These investigations provide new platform and research interest for high-performance in-memory computing technology and sensing-memory-computing all-in-one devices.（1）The spontaneous polarization property of tellurene is discovered and revealed,achieving stable and reliable memory devices without elemental segregation.Tellurene is synthesized via solution process,and its high anisotropy is verified by angle-resolved Raman spectroscopy,second-harmonic generation,and in-situ strain Raman investigations.The manifestation of original polarization domains within highly-oriented tellurene structures,as well as weak ferroelectricity are observed through second-harmonic generation（SHG）and piezoresponse force microscopy（PFM）technologies,confirming the existence of piezoelectric spontaneous polarization properties in tellurene.Further studies on the write-read dynamics of polarization domain confirm the non-volatile memory properties of tellurene,as evidenced by a retention capacity up to 16.5hours.The high Curie temperature and structure stability upto 600K are also investiugated.Moreover,the segregation-free tellurene based field effect transistors achieve large memory window（7000）,low operating voltages(V_DS=100 m V,V_G=2 V),and high current density(36.6μA·μm^-1).（2）A novel route to defect-assisted,soft-phonon dominated photo-carrier relaxation dynamics is established,and the ultra-fast sensing-memory synaptic vision devices using tellurene are realized.The theoretical approach to control the lifetime of photo-carriers are developed in soft-phonon tellurene.Then,the route to introduce Te⁰ vacancy defects in tellurene is researched,as well as the development of photonic synaptic device using tellurene.As a result,tellurene-based optoelectronic synaptic devices exhibit excellent photo-memory performance and high-speed sensing-memory properties.The device achieves retention time of photo-memory as long as 20000 s,and photo memory speed at0.5 MHz,which is three orders of magnitude faster than the instantaneous response of biological systems to light.These devices are successfully applied in mimic biological learning behaviors,achieving 90.06%accuracy in handwriting digit recognition,marking a significant advancement in the field of optoelectronic devices.（3）A highly efficient approach is developed for enhancing the local electric field in tellurene dominated by plasmons,achieving ultra-high sensitivity optical sensing.Through a comprehensive investigation on the structure-function relationship between plasmonic nanostructures and localized electric field effects,an efficient method for enhancing the localized electric field in tellurene is established.Dense Au quantum dots are in-situ grown on the surface of tellurene,realizing strong localized electric field upon surface of tellurene.The tellurene,with highly localized electric fields,achieves high sensitivity optical sensing at the single-molecule level,detectable at concentrations as low as 10^-15 M,coupled with a record-low relative standard deviation（RSD）of signal uniformity at 4.0%.Leveraging the surface-enhanced Raman scattering（SERS）methodology,the developed optical sensor devices demonstrate unparalleled performance in information encryption and decryption.