A main challenge for the development of two-dimensional devices based on atomically thin transition-metal dichalcogenides(TMDs)is the realization of metal–semiconductor junctions(MSJs)with low contact resistance and ...A main challenge for the development of two-dimensional devices based on atomically thin transition-metal dichalcogenides(TMDs)is the realization of metal–semiconductor junctions(MSJs)with low contact resistance and high charge transport capability.However,traditional metal–TMD junctions usually suffer from strong Fermi-level pinning(FLP)and chemical disorder at the interfaces,resulting in weak device performance and high energy consump-tion.By means of high-throughput first-principles calculations,we report an attractive solution via the formation of van der Waals(vdW)contacts between metallic and semiconducting TMDs.We apply a phase-engineering strategy to create a monolayer TMD database for achieving a wide range of work func-tions and band gaps,hence offering a large degree of freedom to construct TMD vdW MSJs with desired contact types.The Schottky barrier heights and contact types of 728 MSJs have been identified and they exhibit weak FLP(-0.62 to-0.90)as compared with the traditional metal–TMD junctions.We find that the interfacial interactions of the MSJs bring a delicate competition between the FLP strength and carrier tunneling efficiency,which can be uti-lized to screen high-performance MSJs.Based on a set of screening criteria,four potential TMD vdW MSJs(e.g.,NiTe_(2)/ZrSe_(2),NiTe_(2)/PdSe_(2),HfTe_(2)/PdTe_(2),TaSe_(2)/MoTe_(2))with Ohmic contact,weak FLP,and high carrier tunneling probability have been predicted.This work not only provides a fundamental understanding of contact properties of TMD vdW MSJs but also renders their huge potential for electronics and optoelectronics.展开更多
Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode a...Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode arrays.It demands the composed photodiodes are reconfigurable,which are usually achieved by ambipolar two-dimensional(2D)semiconductors.To improve the ambipolar charges injection,here we report a top-gated field-effect transistor(FET)design that is of bottom van der Waals contact via transferring ambipolar 2D WSe_(2) onto Pd/Cr source/drain electrodes.The devices exhibit nearly negligible effective barrier heights for both holes and electrons based on thermionic emission mode,and show an almost balanced on/off ratio in the p-branch and n-branch.By replacing the top gate with two aligned semi-gates,the devices can effectively function as reconfigurable photodiodes.They can be switched between PIN and NIP configurations via controlling the two semi-gates,exhibiting good linearity in terms of short-circuit current(ISC)and incident light power density.The photodiode arrays are also demonstrated for in-sensor optoelectronic convolutional image processing,showing significant potential for in-sensor computing image processors.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:62174151Natural Science Foundation of Zhejiang Province,Grant/Award Numbers:LZ22F040003,Q21A050007。
文摘A main challenge for the development of two-dimensional devices based on atomically thin transition-metal dichalcogenides(TMDs)is the realization of metal–semiconductor junctions(MSJs)with low contact resistance and high charge transport capability.However,traditional metal–TMD junctions usually suffer from strong Fermi-level pinning(FLP)and chemical disorder at the interfaces,resulting in weak device performance and high energy consump-tion.By means of high-throughput first-principles calculations,we report an attractive solution via the formation of van der Waals(vdW)contacts between metallic and semiconducting TMDs.We apply a phase-engineering strategy to create a monolayer TMD database for achieving a wide range of work func-tions and band gaps,hence offering a large degree of freedom to construct TMD vdW MSJs with desired contact types.The Schottky barrier heights and contact types of 728 MSJs have been identified and they exhibit weak FLP(-0.62 to-0.90)as compared with the traditional metal–TMD junctions.We find that the interfacial interactions of the MSJs bring a delicate competition between the FLP strength and carrier tunneling efficiency,which can be uti-lized to screen high-performance MSJs.Based on a set of screening criteria,four potential TMD vdW MSJs(e.g.,NiTe_(2)/ZrSe_(2),NiTe_(2)/PdSe_(2),HfTe_(2)/PdTe_(2),TaSe_(2)/MoTe_(2))with Ohmic contact,weak FLP,and high carrier tunneling probability have been predicted.This work not only provides a fundamental understanding of contact properties of TMD vdW MSJs but also renders their huge potential for electronics and optoelectronics.
基金supported by the National Natural Science Foundation of China(No.62274037)the National Key Research and Development Program of China(No.2018YFA0703703)+1 种基金the Ministry of Science and Technology of China(No.2018YFE0118300)State Key Laboratory of ASIC&System(No.2021MS003).
文摘Image sensors with an in-sensor computing architecture have shown great potential in meeting the energy-efficient requirements of emergent data-intensive applications,where images are processed within the photodiode arrays.It demands the composed photodiodes are reconfigurable,which are usually achieved by ambipolar two-dimensional(2D)semiconductors.To improve the ambipolar charges injection,here we report a top-gated field-effect transistor(FET)design that is of bottom van der Waals contact via transferring ambipolar 2D WSe_(2) onto Pd/Cr source/drain electrodes.The devices exhibit nearly negligible effective barrier heights for both holes and electrons based on thermionic emission mode,and show an almost balanced on/off ratio in the p-branch and n-branch.By replacing the top gate with two aligned semi-gates,the devices can effectively function as reconfigurable photodiodes.They can be switched between PIN and NIP configurations via controlling the two semi-gates,exhibiting good linearity in terms of short-circuit current(ISC)and incident light power density.The photodiode arrays are also demonstrated for in-sensor optoelectronic convolutional image processing,showing significant potential for in-sensor computing image processors.