In this work, yttrium-doped zinc oxide （YZO） nanopowder was synthesized via hydrothermal precipitation- method. The microstructure and optical properties of yttrium-doped zinc oxide nanopowder were characterized, wh...In this work, yttrium-doped zinc oxide （YZO） nanopowder was synthesized via hydrothermal precipitation- method. The microstructure and optical properties of yttrium-doped zinc oxide nanopowder were characterized, which confirmed the well-crystalline wurtzite hexagonal phase of ZnO. The yttrium- doped zinc oxide nanopowder grains formed the nanobolts of -400 nm in length and -900 nm in width. High resolution-transmission electron microscopy （HR-TEM） of the nanobolts revealed uniform lattice fringes and no visible faults and/or distortions. X-ray photoelectron spectroscopy （XPS） analysis con- firmed the presence of yttrium in the zinc oxide lattice, proving the contribution of yttrium on the microstructural and optical properties of the material. A strong ultra violet （UV） emission peak of the YZO exhibited a red shift compared to pure zinc oxide, which was ascribed to the defects and the for- mation of a shallow energy level caused bv the incorporation of yttrium.展开更多
Memristive heterostructures,composed of reduced graphene oxide with different degree of reduction,were demonstrated through a simple method of‘direct electron-beam writing’on graphene oxide.Irradiation with an elect...Memristive heterostructures,composed of reduced graphene oxide with different degree of reduction,were demonstrated through a simple method of‘direct electron-beam writing’on graphene oxide.Irradiation with an electron beam at various doses and accelerating voltages made it possible to define highand low-conductivity graphene-oxide areas.The electron beam-reduced graphene oxide/graphene oxide heterostructure clearly exhibited a nonlinear behavior and a well-controlled resistive switching characteristic at a low operating-voltage range(<1 V).The proposed memristive heterostructures are promising for highly-efficient digital storage and information process as well as for analogous neuromorphic computations.展开更多
High-entropy ceramics exhibit novel intrinsic properties.Hence,they have been explored for a wide range of applications ranging from thermal insulation and energy storage to advanced optical components.Recently,the se...High-entropy ceramics exhibit novel intrinsic properties.Hence,they have been explored for a wide range of applications ranging from thermal insulation and energy storage to advanced optical components.Recently,the semiconductor industry has faced a demand for higher-performance chips,necessitating higher aspect ratios in wafer fabrication and further miniaturization of linewidths.Therefore,novel materials with high plasma etching resistance and minimal contaminant generation are needed.The plasma-etching resistance displayed by high-entropy ceramics can be an innovative solution to this emerging challenge.In this study,we successfully fabricated single-phase high-entropy sesquioxide ceramics with high optical transparency,dense microstructure,and minimal residual pores.A structural analysis of the fabricated samples revealed a single-phase structure with excellent phase homogeneity.An evaluation of the plasma-etching resistance of high-entropy ceramics revealed for the first time a low etching rate of 8 nm/h compared with that of conventional plasma-resistant materials.These comprehensive characterizations of high-entropy ceramics indicate that they are promising candidates for significantly improving the production yield of semiconductors and for a wide range of potential applications,such as next-generation active optical ceramics.展开更多
To present an advanced device scheme of high-performance optoelectronic synapses,herein,we demonstrated the electrically-and/or optically-drivable multifaceted synaptic capabilities on the 2D semiconductor channel-bas...To present an advanced device scheme of high-performance optoelectronic synapses,herein,we demonstrated the electrically-and/or optically-drivable multifaceted synaptic capabilities on the 2D semiconductor channel-based ferroelectric field-effect transistor(FeFET)architecture.The device was fabricated in the form of the MoS_(2)/PZT FeFET,and its synaptic weights were effectively controlled by dual stimuli(i.e.,both electrical and optical pulses simultaneously)as well as single stimuli(i.e.,either electrical or optical pulses alone).This could be attributed to the electrical pulse-tunable strong ferroelectric polarization in PbZrxTi_(1−x)O_(3)(PZT)as well as the polarization field-enhanced persistent photoconductivity effect in MoS_(2).Additionally,it was confirmed that the proposed device possesses substantial activity,achieving approximately 95%pattern recognition accuracy.The results substantiate the great potential of the 2D semiconductor channel-based FeFET device as a high-performance optoelectronic synaptic platform,marking a pivotal stride towards the realization of advanced neuromorphic computing systems.展开更多
Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to...Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties.Here,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength.It resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS QDs.We also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative recombination.Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation.Consequently,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots.Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.展开更多
基金supported by the Basic Science Research Program(NRF-2013R1A1A2059900)funded by the Korean government of Ministry of Education(MoE)
文摘In this work, yttrium-doped zinc oxide （YZO） nanopowder was synthesized via hydrothermal precipitation- method. The microstructure and optical properties of yttrium-doped zinc oxide nanopowder were characterized, which confirmed the well-crystalline wurtzite hexagonal phase of ZnO. The yttrium- doped zinc oxide nanopowder grains formed the nanobolts of -400 nm in length and -900 nm in width. High resolution-transmission electron microscopy （HR-TEM） of the nanobolts revealed uniform lattice fringes and no visible faults and/or distortions. X-ray photoelectron spectroscopy （XPS） analysis con- firmed the presence of yttrium in the zinc oxide lattice, proving the contribution of yttrium on the microstructural and optical properties of the material. A strong ultra violet （UV） emission peak of the YZO exhibited a red shift compared to pure zinc oxide, which was ascribed to the defects and the for- mation of a shallow energy level caused bv the incorporation of yttrium.
基金supported financially by the Russian Foundation of Basic Research(Nos.19-29-03050 and 18-29-19120)the National Research Foundation of Korea(Nos.2016R1A6A1A03012877,2017R1D1A1B03035102 and 2017R1A2B4004281).
文摘Memristive heterostructures,composed of reduced graphene oxide with different degree of reduction,were demonstrated through a simple method of‘direct electron-beam writing’on graphene oxide.Irradiation with an electron beam at various doses and accelerating voltages made it possible to define highand low-conductivity graphene-oxide areas.The electron beam-reduced graphene oxide/graphene oxide heterostructure clearly exhibited a nonlinear behavior and a well-controlled resistive switching characteristic at a low operating-voltage range(<1 V).The proposed memristive heterostructures are promising for highly-efficient digital storage and information process as well as for analogous neuromorphic computations.
基金supported by the Fundamental Research Program (PKC2140)of the Korea Institute of Materials Science(KIMS)。
文摘High-entropy ceramics exhibit novel intrinsic properties.Hence,they have been explored for a wide range of applications ranging from thermal insulation and energy storage to advanced optical components.Recently,the semiconductor industry has faced a demand for higher-performance chips,necessitating higher aspect ratios in wafer fabrication and further miniaturization of linewidths.Therefore,novel materials with high plasma etching resistance and minimal contaminant generation are needed.The plasma-etching resistance displayed by high-entropy ceramics can be an innovative solution to this emerging challenge.In this study,we successfully fabricated single-phase high-entropy sesquioxide ceramics with high optical transparency,dense microstructure,and minimal residual pores.A structural analysis of the fabricated samples revealed a single-phase structure with excellent phase homogeneity.An evaluation of the plasma-etching resistance of high-entropy ceramics revealed for the first time a low etching rate of 8 nm/h compared with that of conventional plasma-resistant materials.These comprehensive characterizations of high-entropy ceramics indicate that they are promising candidates for significantly improving the production yield of semiconductors and for a wide range of potential applications,such as next-generation active optical ceramics.
基金supported by the National Research Foundation(NRF)of Korea through the Basic Science Research Programs(Nos.2019R1A2C1085448,2023R1A2C1005421,RS-2024-00356939)funded by the Korean Government.
文摘To present an advanced device scheme of high-performance optoelectronic synapses,herein,we demonstrated the electrically-and/or optically-drivable multifaceted synaptic capabilities on the 2D semiconductor channel-based ferroelectric field-effect transistor(FeFET)architecture.The device was fabricated in the form of the MoS_(2)/PZT FeFET,and its synaptic weights were effectively controlled by dual stimuli(i.e.,both electrical and optical pulses simultaneously)as well as single stimuli(i.e.,either electrical or optical pulses alone).This could be attributed to the electrical pulse-tunable strong ferroelectric polarization in PbZrxTi_(1−x)O_(3)(PZT)as well as the polarization field-enhanced persistent photoconductivity effect in MoS_(2).Additionally,it was confirmed that the proposed device possesses substantial activity,achieving approximately 95%pattern recognition accuracy.The results substantiate the great potential of the 2D semiconductor channel-based FeFET device as a high-performance optoelectronic synaptic platform,marking a pivotal stride towards the realization of advanced neuromorphic computing systems.
基金the financial support from the KIST Institution Program(No.2E32634)Basic Science Research Program through the National Research Foundation of Korea(NRF)grant funded by the Korea government(Ministry of Science and ICT)(Nos.NRF-2017R1A2B3002307 and NRF-2016M3A7B4900135)+1 种基金Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.NRF-2020R1A6A3A01099388)the National R&D Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(Nos.NRF-2022M3H4A1A04074153 and RS-2023-00239634).
文摘Mixed-dimensional composite structures using zero-dimensional(0D)quantum dots(QDs)and two-dimensional(2D)transition metal dichalcogenides(TMDs)materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties.Here,we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide(WSe_(2))/CdSeS QDs monolayer/molybdenum disulfide(MoS_(2))(2D/0D/2D).Specifically,it exhibits an ambipolar photoresponse characteristic,with a negative photoresponse observed in the 400-600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength.It resulted in the high negative responsivity of up to 52.22 mA·W^(−1)under 400 nm,which is 163 times higher than that of the photodetector without CdSeS QDs.We also demonstrated the negative photoresponse,which could be due to increased carrier collision probability and non-radiative recombination.Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation.Consequently,we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots.Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications.
