Construction And Cross-application Of New Two-dimensional Electronic Devices

High-performance electron devices can be used in a variety of leading-edge cross-cutting fields,such as bio-sensors,electronic skin,and artificial intelligence.The importance of obtaining high-performance electron devices motivates the search for new semiconductor materials.The International Technology Roadmap for Semiconductor(ITRS)predicts that the silicon-based electron devices will reach its performance limits by 2020s,so the alternative semiconductor materials are need to extend the Moore's law.Two-dimensional(2D)semiconductor materials have attracted intensive attention because of their unique electronic structure and transport properties in last several decades.Although 2D semiconductor materials,as the next-generation nanoelectronic,have excellent optoelectronic and electronic properties.The core issues in 2D-based devices field are to be addressed,and are still in its infancy.In this work,we developed the new structures 2D field-effect transistors(FETs),and explored its application in neural detection.First,carrier scattering during the transmission of electronic devices,which is caused by inevitable defects in TMDs,remain formidable challenges.To address these issues,a facile,effective and universal patching defect approach that uses a nitrogen plasma doping protocol has been developed in this work,via which the intrinsic vacancies are repaired effectively.To reveal sulfur vacancies and the nature of the nitrogen doping effects,a high-resolution spherical aberration corrected scanning transmission electron microscopy(STEM)was used,which confirmed the N atoms doping in Sulphur vacancies.In this study,a typical TMD material,namely,tungsten disulfide(WS2),is employed to fabricate field-effect transistors(FETs)as a preliminary paradigm to demonstrate our patching defects method.This doping method endows FETs with high electrical performance and excellent contact interface properties.Hence,the additional scattering of multilayered WS2 is significantly reduced and the FETs that are based on the as-repaired materials exhibit a threshold voltage of as low as 3.8 V and a record-high electron field-effect mobility of 184.2 cm2/Vs at room temperature.Furthermore,combined with density functional theory(DFT),the basic physics of our devices is explained.Under a critical SV concentration,nitrogen compensation doping can reduce the electron effective mass,which provides an effective way to improve the carrier mobility of WS2.Following,we report the creation of InSe-Se vertical van der Waals heterostructures,which have a low lattice mismatch of 1.1%and form 2D/2D low-resistance contacts,creating an InSe contact interface that is substantially free from chemical disorder and Fermi-level pinning.The Se layer forms a van der Waals contact to prevent the damage induced by direct metallization and acts as a tunneling layer and protective encapsulation.Using this approach,we achieve heterojunction devices with a high field-effect mobility of?2500 cm2/V·s and an excellent on-state current of?10-3 A at room temperature.Furthermore,the device field-effect mobility degrades by only 3.46%following two months of storage time in open air,which represents the best electrical stability reported to date.In particular,the heterojunction devices exhibit a better photoresponsivity compared with InSe devices in practical application.We employ PMMA layer dielectric and PMMA back-channel encapsulation to effectively improve the electrical stability of InSe while maintaining its high mobility under normal ambient conditions.The hysteresis was maintained at 0.4 V after 30 days of storage under normal ambient conditions,and the threshold voltage shift was retained at 0.6 V with a gate stress VGS of 10 V,which represents the best electrical stability reported to date.Furthermore,density functional theory(DFT)was used to illustrate the basic physics and electrical stability mechanism of our newly configured InSe FETs.The calculation result shows that the increase in electron effective mass is relatively small when InSe forms the heterogeneous junction with PMMA compared to that for other dielectric substrates,which is consistent with the change in FET performance induced by different dielectric substrates.Based on the high electrical stability and field-effect mobility,InSe FETs allow us to conduct the real-time and in situ detection of frog sciatic action potential and designing a pressure sensor based on piezotronic effectThis thesis has enriched the research on the construction and application of high-performance 2D-based electronic devices,laying s solid foundation for its exploration on the understanding of next-generation of nano-electronic devices.