Various methods for production of polysilicon have been proposed for lowering the production cost andenergy consumption, and enhancing productivity, which are critical for industrial applications. The fluidized bed ch...Various methods for production of polysilicon have been proposed for lowering the production cost andenergy consumption, and enhancing productivity, which are critical for industrial applications. The fluidized bed chemical vapor deposition （FBCVD） method is a most promising alternative to conventional ones, but the homogeneous reaction of silane in FBCVD results in unwanted formation of fines, which will affect the product qualityand output. There are some other problems, such as heating degeneration due to undesired polysilicon deposition on the walls of the reactor and the heater. This article mainly reviews the technological development on FBCVD of polycrystalline silicon and the research status for solving the above problems. It also identifies a number of challenges to tackle and principles should be followed in the design ofa FBCVD reactor.展开更多
Monolayer tungsten disulfide （WS2）, a typical member of the semiconducting transition metal dichalcogenide family has drawn considerable interest because of its unique properties. Intriguingly the edge of WS2 exhibi...Monolayer tungsten disulfide （WS2）, a typical member of the semiconducting transition metal dichalcogenide family has drawn considerable interest because of its unique properties. Intriguingly the edge of WS2 exhibits an ideal hydrogen binding energy which makes WS2 a potential alternative to Pt-based electrocatalysts for the hydrogen evolution reaction （HER）. Here, we demonstrate for the first time the successful synthesis of uniform monolayer WS2 nanosheets on centimeter- scale Au foils using a facile, low-pressure chemical vapor deposition method. The edge lengths of the universally observed triangular WS2 nanosheets are tunable from -100 to N1,000 nm. The WS2 nanosheets on Au foils featuring abundant edges were then discovered to be efficient catalysts for the HER, exhibiting a rather high exchange current density of -30.20 μA/cm2 and a small onset potential of Nl10 mV. The effects of coverage and domain size （which correlate closely with the active edge density of WS2） on the electrocatalytic activity were investigated. This work not only provides a novel route toward the batch-production of monolayer WS2 via the introduction of metal foil substrates but also opens up its direct application for facile HER.展开更多
Atomic layer deposition(ALD)has become an indispensable thin-film technology in the contemporary microelectronics industry.The unique self-limited layer-by-layer growth feature of ALD has outstood this technology to d...Atomic layer deposition(ALD)has become an indispensable thin-film technology in the contemporary microelectronics industry.The unique self-limited layer-by-layer growth feature of ALD has outstood this technology to deposit highly uniform conformal pinhole-free thin films with angstrom-level thickness control,particularly on 3D topologies.Over the years,the ALD technology has enabled not only the successful downscaling of the microelectronic devices but also numerous novel 3D device structures.As ALD is essentially a variant of chemical vapor deposition,a comprehensive understanding of the involved chemistry is of crucial importance to further develop and utilize this technology.To this end,we,in this review,focus on the surface chemistry and precursor chemistry aspects of ALD.We first review the surface chemistry of the gas–solid ALD reactions and elaborately discuss the associated mechanisms for the film growth;then,we review the ALD precursor chemistry by comparatively discussing the precursors that have been commonly used in the ALD processes;and finally,we selectively present a few newly-emerged applications of ALD in microelectronics,followed by our perspective on the future of the ALD technology.展开更多
The performance of pearlescent pigment significantly affected by the grain size and the roughness of deposited film. The effect of TiCl_(4) concentration on the initial deposition of TiO_(2) on mica by atmospheric pre...The performance of pearlescent pigment significantly affected by the grain size and the roughness of deposited film. The effect of TiCl_(4) concentration on the initial deposition of TiO_(2) on mica by atmospheric pressure chemical vapor deposition(APCVD) was investigated. The precursor concentration significantly affected the deposition and morphology of TiO_(2) grains assembling the film. The deposition time for fully covering the surface of mica decreased from 120 to 10 s as the TiCl_(4) concentration increased from 0.38%to 2.44%. The grain size increased with the TiCl_(4) concentration. The AFM and TEM analysis demonstrated that the aggregation of TiO_(2) clusters at the initial stage finally result to the agglomeration of fine TiO_(2) grains at high TiCl_(4) concentrations. Following the results, it was suggested that the nucleation density and size was easy to be adjusted when the TiCl_(4) concentration is below 0.90%.展开更多
Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-CH_(4)-H_(2)-Ar system via Chemical Vapor Deposition(CVD),wh...Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-CH_(4)-H_(2)-Ar system via Chemical Vapor Deposition(CVD),which has been found widely applied to C/C composites.Herein,an analysis of the reactions that occur in the initial stage of the CVD-HfC coating process is presented using Density Functional Theory(DFT)and Transition State Theory(TST)at the B3LYP/Lanl2DZ level.The results reveal that HfCl4 can only cleave to produce hypochlorite,which will further react with methyl to synthesize intermediates to form HfC.According to the analysis of the energy barrier and reaction constant,HfCl preferentially reacts with methyl groups to form complex adsorptive intermediates at 1573 K.With a C—Hf bond production energy of 212.8 kcal/mol(1 kcal=4.18 kJ),the reaction rate constant of HfCl+CH is calculated to be 2.15×10^(-18) cm^(3)/s at 1573 K.Additionally,both the simulation and experimental results exhibit that the upward trend of reaction rate constants with temperature is also consistent with the deposition rate,indicating that the growth curve of the reaction rate constants tends to flatten out.The proposed reaction model of the precursor’s decomposition and reconstruction during deposition process has significant implication for the process guidance.展开更多
Advances in energy conversion and storage technologies,such as water electrolyzers,rechargeable metal-air batteries,and fuel cells,have enabled a renewable and sustainable future.The efficiency and effectiveness of th...Advances in energy conversion and storage technologies,such as water electrolyzers,rechargeable metal-air batteries,and fuel cells,have enabled a renewable and sustainable future.The efficiency and effectiveness of these technologies largely relies on the physicochemical properties of the functional materials used,specifically electrocatalysts.Pulsed laser deposition(PLD)is a powerful technique for the synthesis of thin film materials,offering a unique platform for understanding electrochemical reaction mechanisms and searching for low-cost and high-performance electrocatalysts.In this mini-review,we present the latest studies in which thin film materials(mainly focused on perovskite oxide thin films)via PLD have been actively utilized in the field of electrocatalysis.The fundamentals and advantages of PLD in the synthesis of thin films are discussed first.Then,emerging types of thin films associated with electrochemical applications are presented.Special emphasis is placed on material design methods to reveal the reaction mechanisms and establish the structure–performance relationships by understanding structural variations in precatalysts and surface reconstruction under reaction conditions.Finally,we discuss remaining challenges and future perspectives.展开更多
The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region ...The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap.In this paper,the thin-film growth mechanism and process optimization of Zn(O,S)films fabricated using the chemical bath deposition method are sys-tematically investigated.The thickness and quality of Zn(O,S)films were found to be strongly affected by the concentration variation of the precursor chemicals.It was also revealed that different surface morphologies of Zn(O,S)films would appear if the reaction time were changed and,subsequently,the optimum reaction time was defined.The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high.In addition,to further improve the film quality,an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S)thin film was improved by an ammonia etching process followed by an annealing process.For com-parison purposes,both Zn(O,S)-based and CdS-based devices were fabricated and characterized.The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell.展开更多
基金Supported by the Natural Science Foundation of Shandong Province of China （ZR2009BM011） and the Doctor Foundation of Shandong Province of China （BS2010NJ005）.
文摘Various methods for production of polysilicon have been proposed for lowering the production cost andenergy consumption, and enhancing productivity, which are critical for industrial applications. The fluidized bed chemical vapor deposition （FBCVD） method is a most promising alternative to conventional ones, but the homogeneous reaction of silane in FBCVD results in unwanted formation of fines, which will affect the product qualityand output. There are some other problems, such as heating degeneration due to undesired polysilicon deposition on the walls of the reactor and the heater. This article mainly reviews the technological development on FBCVD of polycrystalline silicon and the research status for solving the above problems. It also identifies a number of challenges to tackle and principles should be followed in the design ofa FBCVD reactor.
文摘Monolayer tungsten disulfide （WS2）, a typical member of the semiconducting transition metal dichalcogenide family has drawn considerable interest because of its unique properties. Intriguingly the edge of WS2 exhibits an ideal hydrogen binding energy which makes WS2 a potential alternative to Pt-based electrocatalysts for the hydrogen evolution reaction （HER）. Here, we demonstrate for the first time the successful synthesis of uniform monolayer WS2 nanosheets on centimeter- scale Au foils using a facile, low-pressure chemical vapor deposition method. The edge lengths of the universally observed triangular WS2 nanosheets are tunable from -100 to N1,000 nm. The WS2 nanosheets on Au foils featuring abundant edges were then discovered to be efficient catalysts for the HER, exhibiting a rather high exchange current density of -30.20 μA/cm2 and a small onset potential of Nl10 mV. The effects of coverage and domain size （which correlate closely with the active edge density of WS2） on the electrocatalytic activity were investigated. This work not only provides a novel route toward the batch-production of monolayer WS2 via the introduction of metal foil substrates but also opens up its direct application for facile HER.
基金supported by NSFC(22175005)Guangdong Basic and Applied Basic Research Foundation(2020B1515120039)+1 种基金Shenzhen Fundamental Research Program(JCYJ20200109110628172,GXWD20201231165807007-20200802205241003)Guangdong Technology Center for Oxide Semiconductor Devices and ICs。
文摘Atomic layer deposition(ALD)has become an indispensable thin-film technology in the contemporary microelectronics industry.The unique self-limited layer-by-layer growth feature of ALD has outstood this technology to deposit highly uniform conformal pinhole-free thin films with angstrom-level thickness control,particularly on 3D topologies.Over the years,the ALD technology has enabled not only the successful downscaling of the microelectronic devices but also numerous novel 3D device structures.As ALD is essentially a variant of chemical vapor deposition,a comprehensive understanding of the involved chemistry is of crucial importance to further develop and utilize this technology.To this end,we,in this review,focus on the surface chemistry and precursor chemistry aspects of ALD.We first review the surface chemistry of the gas–solid ALD reactions and elaborately discuss the associated mechanisms for the film growth;then,we review the ALD precursor chemistry by comparatively discussing the precursors that have been commonly used in the ALD processes;and finally,we selectively present a few newly-emerged applications of ALD in microelectronics,followed by our perspective on the future of the ALD technology.
基金the support from National Natural Science Foundation of China (22208355, 22178363 and 21978300)the financial support and mica samples from Changzi Wu and RIKA technology CO., LTD.
文摘The performance of pearlescent pigment significantly affected by the grain size and the roughness of deposited film. The effect of TiCl_(4) concentration on the initial deposition of TiO_(2) on mica by atmospheric pressure chemical vapor deposition(APCVD) was investigated. The precursor concentration significantly affected the deposition and morphology of TiO_(2) grains assembling the film. The deposition time for fully covering the surface of mica decreased from 120 to 10 s as the TiCl_(4) concentration increased from 0.38%to 2.44%. The grain size increased with the TiCl_(4) concentration. The AFM and TEM analysis demonstrated that the aggregation of TiO_(2) clusters at the initial stage finally result to the agglomeration of fine TiO_(2) grains at high TiCl_(4) concentrations. Following the results, it was suggested that the nucleation density and size was easy to be adjusted when the TiCl_(4) concentration is below 0.90%.
基金financially supported by the National Natural Science Foundation of China (Nos. 52293373 and 52130205)the National Key Research and Development Program of China (No. 2021YFA0715803)ND Basic Research Funds of Northwestern Polytechnical University, China (No. G2022WD)
文摘Recently,the preparation of ultra-high temperature HfC ceramic coating has gained significant attention,particularly through the application of the HfCl_(4)-CH_(4)-H_(2)-Ar system via Chemical Vapor Deposition(CVD),which has been found widely applied to C/C composites.Herein,an analysis of the reactions that occur in the initial stage of the CVD-HfC coating process is presented using Density Functional Theory(DFT)and Transition State Theory(TST)at the B3LYP/Lanl2DZ level.The results reveal that HfCl4 can only cleave to produce hypochlorite,which will further react with methyl to synthesize intermediates to form HfC.According to the analysis of the energy barrier and reaction constant,HfCl preferentially reacts with methyl groups to form complex adsorptive intermediates at 1573 K.With a C—Hf bond production energy of 212.8 kcal/mol(1 kcal=4.18 kJ),the reaction rate constant of HfCl+CH is calculated to be 2.15×10^(-18) cm^(3)/s at 1573 K.Additionally,both the simulation and experimental results exhibit that the upward trend of reaction rate constants with temperature is also consistent with the deposition rate,indicating that the growth curve of the reaction rate constants tends to flatten out.The proposed reaction model of the precursor’s decomposition and reconstruction during deposition process has significant implication for the process guidance.
基金National R&D Program through the National Research Foundation of Korea(NRF)(grant nos.2022M3H4A1A01008918 and 2021M3H4A1A01002695)the Korea Research Institute of Chemical Technology Core Research Program funded by the Korea Research Council for Industrial Science and Technology(grant no.KS2222-10).
文摘Advances in energy conversion and storage technologies,such as water electrolyzers,rechargeable metal-air batteries,and fuel cells,have enabled a renewable and sustainable future.The efficiency and effectiveness of these technologies largely relies on the physicochemical properties of the functional materials used,specifically electrocatalysts.Pulsed laser deposition(PLD)is a powerful technique for the synthesis of thin film materials,offering a unique platform for understanding electrochemical reaction mechanisms and searching for low-cost and high-performance electrocatalysts.In this mini-review,we present the latest studies in which thin film materials(mainly focused on perovskite oxide thin films)via PLD have been actively utilized in the field of electrocatalysis.The fundamentals and advantages of PLD in the synthesis of thin films are discussed first.Then,emerging types of thin films associated with electrochemical applications are presented.Special emphasis is placed on material design methods to reveal the reaction mechanisms and establish the structure–performance relationships by understanding structural variations in precatalysts and surface reconstruction under reaction conditions.Finally,we discuss remaining challenges and future perspectives.
基金financially supported by National Key R&D Program of China(grant no.2018YFB1500200).
文摘The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap.In this paper,the thin-film growth mechanism and process optimization of Zn(O,S)films fabricated using the chemical bath deposition method are sys-tematically investigated.The thickness and quality of Zn(O,S)films were found to be strongly affected by the concentration variation of the precursor chemicals.It was also revealed that different surface morphologies of Zn(O,S)films would appear if the reaction time were changed and,subsequently,the optimum reaction time was defined.The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high.In addition,to further improve the film quality,an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S)thin film was improved by an ammonia etching process followed by an annealing process.For com-parison purposes,both Zn(O,S)-based and CdS-based devices were fabricated and characterized.The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell.
