The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the...The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition （ALD） and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide （Al2O3） is used to fabricate the nanostep. There are three steps of Al2O3 in this structure including 8 nm, 18 nm and 44 inn. The thickness of Al2O3 film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al2O3 film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikaliseh-Technische Bundesanstalt （PTB） and the results were 7.5±1.5 nm, 15.5±2.0 nm and 41.8±2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.展开更多
Since the first report of amorphous In–Ga–Zn–O based thin film transistors,interest in oxide semiconductors has grown.They offer high mobility,low off-current,low process temperature,and wide flexibility for compos...Since the first report of amorphous In–Ga–Zn–O based thin film transistors,interest in oxide semiconductors has grown.They offer high mobility,low off-current,low process temperature,and wide flexibility for compositions and processes.Unfortunately,depositing oxide semiconductors using conventional processes like physical vapor deposition leads to problematic issues,especially for high-resolution displays and highly integrated memory devices.Conventional approaches have limited process flexibility and poor conformality on structured surfaces.Atomic layer deposition(ALD)is an advanced technique which can provide conformal,thickness-controlled,and high-quality thin film deposition.Accordingly,studies on ALD based oxide semiconductors have dramatically increased recently.Even so,the relationships between the film properties of ALD-oxide semiconductors and the main variables associated with deposition are still poorly understood,as are many issues related to applications.In this review,to introduce ALD-oxide semiconductors,we provide:(a)a brief summary of the history and importance of ALD-based oxide semiconductors in industry,(b)a discussion of the benefits of ALD for oxide semiconductor deposition(in-situ composition control in vertical distribution/vertical structure engineering/chemical reaction and film properties/insulator and interface engineering),and(c)an explanation of the challenging issues of scaling oxide semiconductors and ALD for industrial applications.This review provides valuable perspectives for researchers who have interest in semiconductor materials and electronic device applications,and the reasons ALD is important to applications of oxide semiconductors.展开更多
ZnTe, CdTe, and the ternary alloy CdZnTe are important semiconductor materials used widely for the detection of an important range of electromagnetic radiation as gamma ray and X-ray. Although, recently these material...ZnTe, CdTe, and the ternary alloy CdZnTe are important semiconductor materials used widely for the detection of an important range of electromagnetic radiation as gamma ray and X-ray. Although, recently these materials have acquired renewed importance due to the new explored nanolayer properties of modern devices. In addition, as shown in this work they can be grown using uncomplicated synthesis techniques based on the deposition in vapour phase of the elemental precursors. This work presents the results obtained from the deposition of nanolayers of these materials using the precursor vapour on GaAs and GaSb (001) substrates. This growth technique, extensively known as atomic layer deposition (ALD), allows the layers growth with nanometric dimension. The main results presented in this work are the used growth parameters and the results of the structural characterization of the layers by the means of Raman spectroscopy measurements. Raman scattering shows the peak corresponding to longitudinal optical (LO)-ZnTe, which is weak and slightly redshift in comparison with that reported for the ZnTe bulk at 210 cm^-1. For the case of the CdTe nanolayer, Raman spectra presented the LO-CdTe peak, which is indicative of the successful growth of the layer. Its weak and slightly redshift in comparison with that reported for the CdTe bulk can be related with the nanometric characteristic of this layer. The performed high-resolution X-ray diffraction (HR-XRD) measurement allows to study some important characteristics such as the crystallinity of the grown layer. In addition, the HR-XRD measurement suggests that the crystalline quality has dependence on the growth temperature.展开更多
Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in ...Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.展开更多
An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The...An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.展开更多
In this work, atomic layer deposition （ALD） was employed to fabricate coaxial multi-interface hollow Ni-A12OB-ZnO nanowires. The morpholog34 microstructure, and ZnO shell thickness dependent electromagnetic and micr...In this work, atomic layer deposition （ALD） was employed to fabricate coaxial multi-interface hollow Ni-A12OB-ZnO nanowires. The morpholog34 microstructure, and ZnO shell thickness dependent electromagnetic and microwave absorbing properties of these Ni-A12OB-ZnO nanowires were characterized. Excellent microwave absorbing properties with a minimum reflection loss （RL） of approximately -50 dB at 9.44 GHz were found for the Ni-A12OB-100ZnO nanowires, which was 10 times of Ni-A1203 nanowires. The microwave absorption frequency could be effectively varied by simply adjusting the number of ZnO deposition cycles. The absorption peaks of Ni-A1203-100ZnO and Ni-A12OB-150ZnO nanowires shifted of 5.5 and 6.8 GHz towards lower frequencies, respectively, occupying one third of the investigated frequency band. The enhanced microwave absorption arose from multiple loss mechanisms caused by the unique coaxial multi-interface structure, such as multi-interfacial polarization relaxation, natural and exchange resonances, as well as multiple internal reflections and scattering. These results demonstrate that the ALD method can be used to realize tailored nanoscale structures, making it a highly promising method for obtaining high- efficiency microwave absorbers, and opening a potentially novel route for frecluencv adiustment and microwave ima^in~ fields.展开更多
In the past decade, nanopores have been developed extensively for various potential applications, and their performance greatly depends on the surface properties of the nanopores. Atomic layer deposition （ALD） is a ...In the past decade, nanopores have been developed extensively for various potential applications, and their performance greatly depends on the surface properties of the nanopores. Atomic layer deposition （ALD） is a new technology for depositing thin films, which has been rapidly developed from a niche technology to an established method. ALD films can cover the surface in confined regions even in nanoscale conformally, thus it is proved to be a powerful tool to modify the surface of the synthetic nanopores and also to fabricate complex nanopores. This review gives a brief introduction on nanopore synthesis and ALD fundamental knowledge, and then focuses on the various aspects of synthetic nanopores processing by ALD and their applications, including single-molecule sensing, nanofiuidic devices, nanostructure fabrication and other applications.展开更多
The current article is a review of recent progress and major trends in the field of flexible oxide thin film transistors（TFTs）, fabricating with atomic layer deposition（ALD） processes. The ALD process offers accur...The current article is a review of recent progress and major trends in the field of flexible oxide thin film transistors（TFTs）, fabricating with atomic layer deposition（ALD） processes. The ALD process offers accurate controlling of film thickness and composition as well as ability of achieving excellent uniformity over large areas at relatively low temperatures. First, an introduction is provided on what is the definition of ALD, the difference among other vacuum deposition techniques, and the brief key factors of ALD on flexible devices. Second, considering functional layers in flexible oxide TFT, the ALD process on polymer substrates may improve device performances such as mobility and stability, adopting as buffer layers over the polymer substrate, gate insulators, and active layers. Third, this review consists of the evaluation methods of flexible oxide TFTs under various mechanical stress conditions. The bending radius and repetition cycles are mostly considering for conventional flexible devices. It summarizes how the device has been degraded/changed under various stress types（directions）. The last part of this review suggests a potential of each ALD film, including the releasing stress, the optimization of TFT structure, and the enhancement of device performance. Thus, the functional ALD layers in flexible oxide TFTs offer great possibilities regarding anti-mechanical stress films, along with flexible display and information storage application fields.展开更多
Atomic layer deposition(ALD)is a thin-film fabrication technique that has great potential in nanofabrication.Based on its self-limiting surface reactions,ALD has excellent conformality,sub-nanometer thickness control,...Atomic layer deposition(ALD)is a thin-film fabrication technique that has great potential in nanofabrication.Based on its self-limiting surface reactions,ALD has excellent conformality,sub-nanometer thickness control,and good process compatibility.These merits promote the industrial and research applications of ALD in various fields.This article provides an introduction to ALD and highlights its applications in semiconductors,pan-semiconductors,environment and energy,and other fields.The applications of ALD in the key nodes of integrated circuits are initially demonstrated,and the areaselective ALD technique is discussed as a bottom-up method for self-aligned nanomanufacturing.Emerging applications of ALD are illustrated in the fabrication of passivation layers,functional surface layers,and buffer layers,which have shown the development trend of ALD in miniaturization and diversification.ALD is an enabling technique for atomic and closeto-atomic scale manufacturing(ACSM)of materials,structures,devices,and systems in versatile applications.The use of theory calculation,multiscale simulation,and more novel methods would steer ALD into further evolution,which makes it possible to cater to the demand of ACSM.展开更多
Currently,there has an ever-growing interest in layered LiNi_(x)Mn_(y)Co_(z)O_(2)(NMCs,x+y+z=1)cathode materials for lithium-ion batteries(LIBs)and lithium metal batteries(LMBs),due to their low cost and high capacity...Currently,there has an ever-growing interest in layered LiNi_(x)Mn_(y)Co_(z)O_(2)(NMCs,x+y+z=1)cathode materials for lithium-ion batteries(LIBs)and lithium metal batteries(LMBs),due to their low cost and high capacity.However,they still suffer from a series of issues,such as Li/Ni cation mixing,irreversible phase transition,and transition metal dissolution.These issues result in severe capacity degradation and limited cyclability of NMCs.Recently,atomic and molecular layer deposition(ALD and MLD)have emerged as a novel tool to tackle these issues,featuring their unique capabilities to fine-tailor NMCs'surfaces for stable interfaces and improved electrochemical performance in LIBs and LMBs.In this review,we specially summarize the recent advances of different ALD and MLD coatings on NMCs and discuss their working mechanisms.We expect that this review will stimulate more efforts to further develop better NMCs using novel ALD/MLD coatings.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51175418)Major Research Program on Nanomanufacturing of National Natural Science Foundation of China(Grant No.91323303)+1 种基金Fund of the State Key Laboratory of Precision Measuring Technology and Instruments(Tianjin University and Tsinghua University)of China(Grant No.PIL1403)Collaborative Innovation Center of Suzhou Nano Science and Technology of China
文摘The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition （ALD） and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide （Al2O3） is used to fabricate the nanostep. There are three steps of Al2O3 in this structure including 8 nm, 18 nm and 44 inn. The thickness of Al2O3 film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al2O3 film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikaliseh-Technische Bundesanstalt （PTB） and the results were 7.5±1.5 nm, 15.5±2.0 nm and 41.8±2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.
基金supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2020M3H4A3081867)the industry technology R&D program (20006400) funded by the Ministry of Trade,Industry and Energy (MOTIE, Korea)+2 种基金the project number 20010402 funded by the Ministry of Trade,Industry and Energy (MOTIE, Korea)the Industry Technology R&D program (#20010371) funded by the Ministry of Trade,Industry and Energy (MOTIE, Republic of Korea)the Technology Innovation Program (20017382) funded By the Ministryof Trade,Industry and Energy (MOTIE, Korea)
文摘Since the first report of amorphous In–Ga–Zn–O based thin film transistors,interest in oxide semiconductors has grown.They offer high mobility,low off-current,low process temperature,and wide flexibility for compositions and processes.Unfortunately,depositing oxide semiconductors using conventional processes like physical vapor deposition leads to problematic issues,especially for high-resolution displays and highly integrated memory devices.Conventional approaches have limited process flexibility and poor conformality on structured surfaces.Atomic layer deposition(ALD)is an advanced technique which can provide conformal,thickness-controlled,and high-quality thin film deposition.Accordingly,studies on ALD based oxide semiconductors have dramatically increased recently.Even so,the relationships between the film properties of ALD-oxide semiconductors and the main variables associated with deposition are still poorly understood,as are many issues related to applications.In this review,to introduce ALD-oxide semiconductors,we provide:(a)a brief summary of the history and importance of ALD-based oxide semiconductors in industry,(b)a discussion of the benefits of ALD for oxide semiconductor deposition(in-situ composition control in vertical distribution/vertical structure engineering/chemical reaction and film properties/insulator and interface engineering),and(c)an explanation of the challenging issues of scaling oxide semiconductors and ALD for industrial applications.This review provides valuable perspectives for researchers who have interest in semiconductor materials and electronic device applications,and the reasons ALD is important to applications of oxide semiconductors.
文摘ZnTe, CdTe, and the ternary alloy CdZnTe are important semiconductor materials used widely for the detection of an important range of electromagnetic radiation as gamma ray and X-ray. Although, recently these materials have acquired renewed importance due to the new explored nanolayer properties of modern devices. In addition, as shown in this work they can be grown using uncomplicated synthesis techniques based on the deposition in vapour phase of the elemental precursors. This work presents the results obtained from the deposition of nanolayers of these materials using the precursor vapour on GaAs and GaSb (001) substrates. This growth technique, extensively known as atomic layer deposition (ALD), allows the layers growth with nanometric dimension. The main results presented in this work are the used growth parameters and the results of the structural characterization of the layers by the means of Raman spectroscopy measurements. Raman scattering shows the peak corresponding to longitudinal optical (LO)-ZnTe, which is weak and slightly redshift in comparison with that reported for the ZnTe bulk at 210 cm^-1. For the case of the CdTe nanolayer, Raman spectra presented the LO-CdTe peak, which is indicative of the successful growth of the layer. Its weak and slightly redshift in comparison with that reported for the CdTe bulk can be related with the nanometric characteristic of this layer. The performed high-resolution X-ray diffraction (HR-XRD) measurement allows to study some important characteristics such as the crystallinity of the grown layer. In addition, the HR-XRD measurement suggests that the crystalline quality has dependence on the growth temperature.
文摘Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of X-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplating protocol that reliably filled trenches for such structures.
文摘An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.
文摘In this work, atomic layer deposition （ALD） was employed to fabricate coaxial multi-interface hollow Ni-A12OB-ZnO nanowires. The morpholog34 microstructure, and ZnO shell thickness dependent electromagnetic and microwave absorbing properties of these Ni-A12OB-ZnO nanowires were characterized. Excellent microwave absorbing properties with a minimum reflection loss （RL） of approximately -50 dB at 9.44 GHz were found for the Ni-A12OB-100ZnO nanowires, which was 10 times of Ni-A1203 nanowires. The microwave absorption frequency could be effectively varied by simply adjusting the number of ZnO deposition cycles. The absorption peaks of Ni-A1203-100ZnO and Ni-A12OB-150ZnO nanowires shifted of 5.5 and 6.8 GHz towards lower frequencies, respectively, occupying one third of the investigated frequency band. The enhanced microwave absorption arose from multiple loss mechanisms caused by the unique coaxial multi-interface structure, such as multi-interfacial polarization relaxation, natural and exchange resonances, as well as multiple internal reflections and scattering. These results demonstrate that the ALD method can be used to realize tailored nanoscale structures, making it a highly promising method for obtaining high- efficiency microwave absorbers, and opening a potentially novel route for frecluencv adiustment and microwave ima^in~ fields.
基金This work was financially supported by the Ministry of Science and Technology of China （Grant No. 2010CB832904）, NSAF （Grant No. U1230111）, and the National Natural Science Foundation of China （NSFC Grant Nos. 91226202, 11175024 and 11375031）.
文摘In the past decade, nanopores have been developed extensively for various potential applications, and their performance greatly depends on the surface properties of the nanopores. Atomic layer deposition （ALD） is a new technology for depositing thin films, which has been rapidly developed from a niche technology to an established method. ALD films can cover the surface in confined regions even in nanoscale conformally, thus it is proved to be a powerful tool to modify the surface of the synthetic nanopores and also to fabricate complex nanopores. This review gives a brief introduction on nanopore synthesis and ALD fundamental knowledge, and then focuses on the various aspects of synthetic nanopores processing by ALD and their applications, including single-molecule sensing, nanofiuidic devices, nanostructure fabrication and other applications.
基金supported by the National Research Foundation of Korea(NRF)(No.NRF-2017RID1A1B03034035)the Ministry of Trade,Industry&Energy(No.#10051403)the Korea Semiconductor Research Consortium
文摘The current article is a review of recent progress and major trends in the field of flexible oxide thin film transistors（TFTs）, fabricating with atomic layer deposition（ALD） processes. The ALD process offers accurate controlling of film thickness and composition as well as ability of achieving excellent uniformity over large areas at relatively low temperatures. First, an introduction is provided on what is the definition of ALD, the difference among other vacuum deposition techniques, and the brief key factors of ALD on flexible devices. Second, considering functional layers in flexible oxide TFT, the ALD process on polymer substrates may improve device performances such as mobility and stability, adopting as buffer layers over the polymer substrate, gate insulators, and active layers. Third, this review consists of the evaluation methods of flexible oxide TFTs under various mechanical stress conditions. The bending radius and repetition cycles are mostly considering for conventional flexible devices. It summarizes how the device has been degraded/changed under various stress types（directions）. The last part of this review suggests a potential of each ALD film, including the releasing stress, the optimization of TFT structure, and the enhancement of device performance. Thus, the functional ALD layers in flexible oxide TFTs offer great possibilities regarding anti-mechanical stress films, along with flexible display and information storage application fields.
基金the National NaturalScienceFoundationofChina(51835005,51871103,and 51911540476)National Key Research and Development Program of China(2020YFB2010401)+1 种基金the Hubei Province Natural Science Foundation for innovative research groups(2020CFA030)Tencent Foundation and the Independent Innovation Research Fund of Huazhong UniversityofScienceandTechnology(2019kfyXMBZ025)。
文摘Atomic layer deposition(ALD)is a thin-film fabrication technique that has great potential in nanofabrication.Based on its self-limiting surface reactions,ALD has excellent conformality,sub-nanometer thickness control,and good process compatibility.These merits promote the industrial and research applications of ALD in various fields.This article provides an introduction to ALD and highlights its applications in semiconductors,pan-semiconductors,environment and energy,and other fields.The applications of ALD in the key nodes of integrated circuits are initially demonstrated,and the areaselective ALD technique is discussed as a bottom-up method for self-aligned nanomanufacturing.Emerging applications of ALD are illustrated in the fabrication of passivation layers,functional surface layers,and buffer layers,which have shown the development trend of ALD in miniaturization and diversification.ALD is an enabling technique for atomic and closeto-atomic scale manufacturing(ACSM)of materials,structures,devices,and systems in versatile applications.The use of theory calculation,multiscale simulation,and more novel methods would steer ALD into further evolution,which makes it possible to cater to the demand of ACSM.
基金partial support from the National Science Foundation(No.2132578)the financial research support of the Chancellor's Fund from the University of Arkansas,Fayetteville,AR,USA。
文摘Currently,there has an ever-growing interest in layered LiNi_(x)Mn_(y)Co_(z)O_(2)(NMCs,x+y+z=1)cathode materials for lithium-ion batteries(LIBs)and lithium metal batteries(LMBs),due to their low cost and high capacity.However,they still suffer from a series of issues,such as Li/Ni cation mixing,irreversible phase transition,and transition metal dissolution.These issues result in severe capacity degradation and limited cyclability of NMCs.Recently,atomic and molecular layer deposition(ALD and MLD)have emerged as a novel tool to tackle these issues,featuring their unique capabilities to fine-tailor NMCs'surfaces for stable interfaces and improved electrochemical performance in LIBs and LMBs.In this review,we specially summarize the recent advances of different ALD and MLD coatings on NMCs and discuss their working mechanisms.We expect that this review will stimulate more efforts to further develop better NMCs using novel ALD/MLD coatings.
基金National Ministry of Science and Technology“13thFive-Year”Key Research and Development Program Sub Project for High Performance Computing(2016YFB0200205)2018 Shanghai Public R&D Service Center Construction Project(18DZ2295400)
