Microbial cellulose （MC） membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide （ITO） electrodes.Transparent and conductive ITO thin ...Microbial cellulose （MC） membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide （ITO） electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency （RF） magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction （XRD）,scanning electron microscopy （SEM）,atomic force mi-croscopy （AFM）,and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content （O2/Ar,volume ratio） in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ～120 Ω·square-1 （Ω·sq-1）] and transparent （above 76%） ITO thin films （240 nm thick） were obtained with a moderate sputtering power （about 60 W） and with an oxygen flow rate of 0.25 ml·min-1 （sccm） during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.展开更多
The electrical and optical properties of the indium tin oxide （ITO）/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the v...The electrical and optical properties of the indium tin oxide （ITO）/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.展开更多
The time and temperature dependence of threshold voltage shift under positive-bias stress（PBS） and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide（a-IGZO） thin-film transisto...The time and temperature dependence of threshold voltage shift under positive-bias stress（PBS） and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide（a-IGZO） thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτ stress= 0.72 eV for the PBS process and an average effective energy barrier Eτ recovery= 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development.展开更多
Indium tin oxide （ITO） ultrathin films were prepared on glass substrate by DC （direct current） magnetron sputtering technique with the assistance of H2O vapor to avoid potential surface damage. The film properties...Indium tin oxide （ITO） ultrathin films were prepared on glass substrate by DC （direct current） magnetron sputtering technique with the assistance of H2O vapor to avoid potential surface damage. The film properties were characterized by X-ray diffraction （XRD） technique, four-point probe method and spectrophotometer. The results show that the deposited ITO film with introduced H2O during sputtering process was almost amorphous. The average visible light transmission of 100 nm ITO film was around 85% and square resistivity was below 80 Ω/square. The film was used as the transparent anode to fabricate an inverted top-emitting organic light-emitting diodes （IT-OLEDs） with the structure of glass substrate/Alq3 （40 nm）/NPB （15 nm）/CuPc （x nm）/ITO anode （100 nm）, where the film thickness of CuPc was optimized. It was found that the luminance of this IT-OLEDs was improved from 25 cd/m^2 to more than 527 cd/m^2 by increasing the thickness of CuPc, and luminance efficiency of 0.24 lm/W at 100 cd/m^2 was obtained, which indicated that the optimized thickness of CuPc layer was around 15 nm.展开更多
Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of ace...Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82 × 10^-3 Ω. cm and particle grains. The doublelayers structure is designed to fabricate the ZnO：In thin film with low resistivity （2.58 × 10^-3 Ω. cm） and good surface morphology. It is found that the surface morphology of the double-layer ZnO：In film strongly depends on the substratelayer, and the second-layer plays a large part in the resistivity of the doublewlayer ZnO：In thin film. Both total and direct transmittances of the double-layer ZnO：In film are above 80% in the visible light region. Single junction a-Si：H solar cell based on the double-layer ZnO：In as front electrode is also investigated.展开更多
Low-frequency noise（LFN） in all operation regions of amorphous indium zinc oxide（a-IZO） thin film transistors（TFTs） with an aluminum oxide gate insulator is investigated. Based on the LFN measured results, we ex...Low-frequency noise（LFN） in all operation regions of amorphous indium zinc oxide（a-IZO） thin film transistors（TFTs） with an aluminum oxide gate insulator is investigated. Based on the LFN measured results, we extract the distribution of localized states in the band gap and the spatial distribution of border traps in the gate dielectric,and study the dependence of measured noise on the characteristic temperature of localized states for a-IZO TFTs with Al2 O3 gate dielectric. Further study on the LFN measured results shows that the gate voltage dependent noise data closely obey the mobility fluctuation model, and the average Hooge＇s parameter is about 1.18×10^-3.Considering the relationship between the free carrier number and the field effect mobility, we simulate the LFN using the △N-△μ model, and the total trap density near the IZO/oxide interface is about 1.23×10^18 cm^-3eV^-1.展开更多
The post-deposition heat treatment (annealing) for the electrochemically deposited thin film is often necessary in order to improve its crystallinity. In the present study, the electrochemically deposited indium sulfi...The post-deposition heat treatment (annealing) for the electrochemically deposited thin film is often necessary in order to improve its crystallinity. In the present study, the electrochemically deposited indium sulfide oxide thin film was annealed in sulphure atmosphere for 60 min at 150℃ and 300℃. The impact of the annealing process on the composition, crystal structure, and surface morphology of the thin film was investigated. In addition, superstrate heterojunction solar cells based on the annealed film as a buffer layer and tin sulphide as an active layer were fabricated and characterized. They showed diode-like behavior under dark condition and a relatively small photovoltaic effect under AM1.5 illumination condition.展开更多
In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transist...In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metalsemiconductor junction.展开更多
The present work mainly describes the technology for preparing indium-tin oxide （ITO） targets by cold isostatic pressing （CIP） and normal pressure sintering process. ITO powders were produced by chemical co-precip...The present work mainly describes the technology for preparing indium-tin oxide （ITO） targets by cold isostatic pressing （CIP） and normal pressure sintering process. ITO powders were produced by chemical co-precipitation and shaped into an ITO green compact with a relative density of 60% by CIP under 300 MPa. Then, an ITO target with a relative density larger than 99.6% was obtained by sintering this green compact at 1550℃ for 8 h. The effects of forming pressure, sintering temperature and sintering time on the density of the target were inves- tigated. Also, a discussion was made on the sintering atmosphere.展开更多
High throughput experimental methods are known to accelerate the rate of research,development,and deployment of electronic materials.For example,thin films with lateral gradients in composition,thickness,or other para...High throughput experimental methods are known to accelerate the rate of research,development,and deployment of electronic materials.For example,thin films with lateral gradients in composition,thickness,or other parameters have been used alongside spatially-resolved characterization to assess how various physical factors affect the material properties under varying measurement conditions.Similarly,multi-layer electronic devices that contain such graded thin films as one or more of their layers can also be characterized spatially in order to optimize the performance.In this work,we apply these high throughput experimental methods to thin film transistors(TFTs),demonstrating combinatorial channel layer growth,device fabrication,and semi-automated characterization using sputtered oxide TFTs as a case study.We show that both extrinsic and intrinsic types of device gradients can be generated in a TFT library,such as channel thickness and length,channel cation compositions,and oxygen atmosphere during deposition.We also present a semi-automated method to measure the 44 devices fabricated on a 50 mm×50 mm substrate that can help to identify properly functioning TFTs in the library and finish the measurement in a short time.Finally,we propose a fully automated characterization system for similar TFT libraries,which can be coupled with high throughput data analysis.These results demonstrate that high throughput methods can accelerate the investigation of TFTs and other electronic devices.展开更多
Under the action of a positive gate bias stress, a hump in the subthreshold region of the transfer characteristic is observed for the amorphous indium-gallium-zinc oxide thin film transistor, which adopts an elevated-...Under the action of a positive gate bias stress, a hump in the subthreshold region of the transfer characteristic is observed for the amorphous indium-gallium-zinc oxide thin film transistor, which adopts an elevated-metal metal-oxide structure. As stress time goes by, both the on-state current and the hump shift towards the negative gate-voltage direction. The humps occur at almost the same current levels for devices with different channel widths, which is attributed to the parasitic transistors located at the channel width edges. Therefore, we propose that the positive charges trapped at the back-channel interface cause the negative shift, and the origin of the hump is considered as being due to more positive charges trapped at the edges along the channel width direction. On the other hand, the hump-effect becomes more significant in a short channel device （L=2 μm）. It is proposed that the diffusion of oxygen vacancies takes place from the high concentration source/drain region to the intrinsic channel region.展开更多
The Indium tin oxide（ITO） thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor.To obtain high-quality ITO films through sol-gel method, the ionic surfactant ...The Indium tin oxide（ITO） thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor.To obtain high-quality ITO films through sol-gel method, the ionic surfactant monoethanolamine and the non-ionic surfactant polyethylene glycol（PEG） were added to the ITO precursor slurry.The influences of surfactants on the structural and photoelectric properties of ITO film samples were investigated.XRD patterns indicated that surfactant monoethanolamine contributed to film predominant grain orientation along the（400） plane.The high transmittance（over 95%） was attributed to the preferred orientation and the grain size expansion of ITO films.SEM showed that the surface particle size and the morphology of ITO films were strongly dependent on the kind of surfactants used.Moving to the shortwave region, the absorption edge of the films exhibited the Burstein-Moss shift.展开更多
Indium tin oxide （ITO） thin films were prepared on alumina ceramic substrates by radio frequency magnetron sputtering. The samples were subsequently annealed in air at temperatures ranging from 500 to 1,100 ℃ for 1...Indium tin oxide （ITO） thin films were prepared on alumina ceramic substrates by radio frequency magnetron sputtering. The samples were subsequently annealed in air at temperatures ranging from 500 to 1,100 ℃ for 1 h. The influences of the annealing temperature on the microstructure and electrical properties of the ITO thin films were investigated, and the results indicate that the as-deposited ITO thin films are amorphous in nature. All samples were crystallized by annealing at 500 ~C. As the annealing temperature increases, the predominant orientation shifts from （222） to （400）. The carrier concentration decreases initially and then increases when the annealing temperature rises beyond 1,000 ℃. The resistivity of the ITO thin films increases smoothly as the annealing temperature increases to just below 900 ℃. Beyond 900 ℃, however, the resistivity of the films increases sharply. The annealing temperature has a significant effect on the stability of the ITO/Pt thin film thermocouples （TFTCs）. TFTCs annealed at 1,000 ℃ show improved high- temperature stability and Seebeck coefficients of up to 77.73 pV/℃.展开更多
Carbon nanotubes （CNTs） have emerged as an important material for printed macroelectronics. However, achieving printed complementary macroelectronics solely based on CNTs is difficult because it is still challenging...Carbon nanotubes （CNTs） have emerged as an important material for printed macroelectronics. However, achieving printed complementary macroelectronics solely based on CNTs is difficult because it is still challenging to make reliable n-type CNT transistors. In this study, we report threshold voltage （Vth） tuning and printing of complementary transistors and inverters composed of thin films of CNTs and indium zinc oxide （IZO） as p-type and n-type transistors, respectively. We have optimized the Vth of p-type transistors by comparing Ti/Au and Ti/Pd as source/drain electrodes, and observed that CNT transistors with Ti/Au electrodes exhibited enhancement mode operation （Vth 〈 0）. In addition, the optimized In：Zn ratio offers good n-type transistors with high on-state current （Ion） and enhancement mode operation （Vth 〉 0）. For example, an In：Zn ratio of 2：1 yielded an enhancement mode n-type transistor with Vth - 1 V and Ion of 5.2 μA. Furthermore, by printing a CNT thin film and an IZO thin film on the same substrate, we have fabricated a complementary inverter with an output swing of 99.6% of the supply voltage and a voltage gain of 16.9. This work shows the promise of the hybrid integration of p-type CNT and n-type IZO for complementary transistors and circuits.展开更多
Niobium-doped indium tin oxide （ITO：Nb） thin films are fabricated on glass substrates by radio frequency （RF） magnetron sputtering at different temperatures. Structural, electrical and optical properties of the f...Niobium-doped indium tin oxide （ITO：Nb） thin films are fabricated on glass substrates by radio frequency （RF） magnetron sputtering at different temperatures. Structural, electrical and optical properties of the films are investigated using X-ray diffraction （XRD）, atomic force microscopy （AFM）, ultraviolet-visible （UV-VIS） spectroscopy and electrical measurements. XRD patterns show that the preferential orientation ofpolycrystalline structure changes from （400） to （222） crystal plane, and the crystallite size increases with the increase of substrate temperature. AFM analyses reveal that the film is very smooth at low temperature. The root mean square （RMS） roughness and the average roughness are 2.16 nm and 1.64 nm, respectively. The obtained lowest resistivity of the films is 1.2 × 10^4 Ω-cm, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 16.5 cmVV.s and 1.88× 10^21 cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which is varied from 3.49 eV to 3.63 eV.展开更多
基金Supported by the National Natural Science Foundation of China （10776014） Nanjing University of Science and Technology （NUST） Research Funding
文摘Microbial cellulose （MC） membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide （ITO） electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency （RF） magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction （XRD）,scanning electron microscopy （SEM）,atomic force mi-croscopy （AFM）,and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content （O2/Ar,volume ratio） in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ～120 Ω·square-1 （Ω·sq-1）] and transparent （above 76%） ITO thin films （240 nm thick） were obtained with a moderate sputtering power （about 60 W） and with an oxygen flow rate of 0.25 ml·min-1 （sccm） during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.61222501 and 61335004)
文摘The electrical and optical properties of the indium tin oxide （ITO）/epoxy composite exhibit dramatic variations as functions of the ITO composition and ITO particle size. Sharp increases in the conductivity in the vicinity of a critical volume fraction have been found within the framework of percolation theory. A conductive and insulating transition model is extracted by the ITO particle network in the SEM image, and verified by the resistivity dependence on the temperature. The dependence of the optical transmittance on the particle size was studied. Further decreasing the ITO particle size could further improve the percolation threshold and light transparency of the composite film.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CB301900 and 2011CB922100)the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘The time and temperature dependence of threshold voltage shift under positive-bias stress（PBS） and the following recovery process are investigated in amorphous indium-gallium-zinc-oxide（a-IGZO） thin-film transistors. It is found that the time dependence of threshold voltage shift can be well described by a stretched exponential equation in which the time constant τ is found to be temperature dependent. Based on Arrhenius plots, an average effective energy barrier Eτ stress= 0.72 eV for the PBS process and an average effective energy barrier Eτ recovery= 0.58 eV for the recovery process are extracted respectively. A charge trapping/detrapping model is used to explain the threshold voltage shift in both the PBS and the recovery process. The influence of gate bias stress on transistor performance is one of the most critical issues for practical device development.
基金supported by the National Natural Science Foundation of China under Grants No.60425101Young Excellence Project of University of Electronic Science and Technology of China(UESTC-060206)project.
文摘Indium tin oxide （ITO） ultrathin films were prepared on glass substrate by DC （direct current） magnetron sputtering technique with the assistance of H2O vapor to avoid potential surface damage. The film properties were characterized by X-ray diffraction （XRD） technique, four-point probe method and spectrophotometer. The results show that the deposited ITO film with introduced H2O during sputtering process was almost amorphous. The average visible light transmission of 100 nm ITO film was around 85% and square resistivity was below 80 Ω/square. The film was used as the transparent anode to fabricate an inverted top-emitting organic light-emitting diodes （IT-OLEDs） with the structure of glass substrate/Alq3 （40 nm）/NPB （15 nm）/CuPc （x nm）/ITO anode （100 nm）, where the film thickness of CuPc was optimized. It was found that the luminance of this IT-OLEDs was improved from 25 cd/m^2 to more than 527 cd/m^2 by increasing the thickness of CuPc, and luminance efficiency of 0.24 lm/W at 100 cd/m^2 was obtained, which indicated that the optimized thickness of CuPc layer was around 15 nm.
基金supported by Hi-Tech Research and Development Program of China (Grant Nos. 2007AA05Z436 and 2009AA050602)Science and Technology Support Project of Tianjin (Grant No. 08ZCKFGX03500)+3 种基金the National Basic Research Program of China (Grant Nos. 2011CB201605 and 2011CB201606)the National Natural Science Foundation of China (Grant No. 60976051)International Cooperation Project between China-Greece Government (Grant No. 2009DFA62580)Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0295)
文摘Indium doped zinc oxide （ZnO：In） thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate. 1 and 2 at.% indium doped single-layer ZnO：In thin films with different amounts of acetic acid added in the initial solution were fabricated. The 1 at.% indium doped single-layers have triangle grains. The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82 × 10^-3 Ω. cm and particle grains. The doublelayers structure is designed to fabricate the ZnO：In thin film with low resistivity （2.58 × 10^-3 Ω. cm） and good surface morphology. It is found that the surface morphology of the double-layer ZnO：In film strongly depends on the substratelayer, and the second-layer plays a large part in the resistivity of the doublewlayer ZnO：In thin film. Both total and direct transmittances of the double-layer ZnO：In film are above 80% in the visible light region. Single junction a-Si：H solar cell based on the double-layer ZnO：In as front electrode is also investigated.
基金Supported by the National Natural Science Foundation of China under Grant No 61574048the Science and Technology Research Project of Guangdong Province under Grant Nos 2015B090912002 and 2015B090901048the Pearl River S&T Nova Program of Guangzhou under Grant No 201710010172
文摘Low-frequency noise（LFN） in all operation regions of amorphous indium zinc oxide（a-IZO） thin film transistors（TFTs） with an aluminum oxide gate insulator is investigated. Based on the LFN measured results, we extract the distribution of localized states in the band gap and the spatial distribution of border traps in the gate dielectric,and study the dependence of measured noise on the characteristic temperature of localized states for a-IZO TFTs with Al2 O3 gate dielectric. Further study on the LFN measured results shows that the gate voltage dependent noise data closely obey the mobility fluctuation model, and the average Hooge＇s parameter is about 1.18×10^-3.Considering the relationship between the free carrier number and the field effect mobility, we simulate the LFN using the △N-△μ model, and the total trap density near the IZO/oxide interface is about 1.23×10^18 cm^-3eV^-1.
文摘The post-deposition heat treatment (annealing) for the electrochemically deposited thin film is often necessary in order to improve its crystallinity. In the present study, the electrochemically deposited indium sulfide oxide thin film was annealed in sulphure atmosphere for 60 min at 150℃ and 300℃. The impact of the annealing process on the composition, crystal structure, and surface morphology of the thin film was investigated. In addition, superstrate heterojunction solar cells based on the annealed film as a buffer layer and tin sulphide as an active layer were fabricated and characterized. They showed diode-like behavior under dark condition and a relatively small photovoltaic effect under AM1.5 illumination condition.
基金Project supported by the Key Industrial R&D Program of Jiangsu Province,China(Grant No.BE2015155)the Priority Academic Program Development of Higher Education Institutions of Jiangsu Province,Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.021014380033)
文摘In this work, a method based on scanning Kelvin probe microscopy is proposed to separately extract source/drain（S/D） series resistance in operating amorphous indium–gallium–zinc–oxide（a-IGZO） thin-film transistors. The asymmetry behavior of S/D contact resistance is deduced and the underlying physics is discussed. The present results suggest that the asymmetry of S/D contact resistance is caused by the difference in bias conditions of the Schottky-like junction at the contact interface induced by the parasitic reaction between contact metal and a-IGZO. The overall contact resistance should be determined by both the bulk channel resistance of the contact region and the interface properties of the metalsemiconductor junction.
基金supported by the National High-Tech Research and Development Program of China(No. 2004AA303542)
文摘The present work mainly describes the technology for preparing indium-tin oxide （ITO） targets by cold isostatic pressing （CIP） and normal pressure sintering process. ITO powders were produced by chemical co-precipitation and shaped into an ITO green compact with a relative density of 60% by CIP under 300 MPa. Then, an ITO target with a relative density larger than 99.6% was obtained by sintering this green compact at 1550℃ for 8 h. The effects of forming pressure, sintering temperature and sintering time on the density of the target were inves- tigated. Also, a discussion was made on the sintering atmosphere.
基金the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308Funding provided by Laboratory Directed Research and Development (LDRD) program at NREL. Y. H+1 种基金support from Science and Technology Commission of Shanghai Municipality (Grant No. 16JC1400603)a grant from the National Natural Science Foundation of China (Grant No. 61471126)
文摘High throughput experimental methods are known to accelerate the rate of research,development,and deployment of electronic materials.For example,thin films with lateral gradients in composition,thickness,or other parameters have been used alongside spatially-resolved characterization to assess how various physical factors affect the material properties under varying measurement conditions.Similarly,multi-layer electronic devices that contain such graded thin films as one or more of their layers can also be characterized spatially in order to optimize the performance.In this work,we apply these high throughput experimental methods to thin film transistors(TFTs),demonstrating combinatorial channel layer growth,device fabrication,and semi-automated characterization using sputtered oxide TFTs as a case study.We show that both extrinsic and intrinsic types of device gradients can be generated in a TFT library,such as channel thickness and length,channel cation compositions,and oxygen atmosphere during deposition.We also present a semi-automated method to measure the 44 devices fabricated on a 50 mm×50 mm substrate that can help to identify properly functioning TFTs in the library and finish the measurement in a short time.Finally,we propose a fully automated characterization system for similar TFT libraries,which can be coupled with high throughput data analysis.These results demonstrate that high throughput methods can accelerate the investigation of TFTs and other electronic devices.
基金Project supported by the Science and Technology Program of Suzhou City,China(Grant No.SYG201538)the National Natural Science Foundation of China(Grant No.61574096)
文摘Under the action of a positive gate bias stress, a hump in the subthreshold region of the transfer characteristic is observed for the amorphous indium-gallium-zinc oxide thin film transistor, which adopts an elevated-metal metal-oxide structure. As stress time goes by, both the on-state current and the hump shift towards the negative gate-voltage direction. The humps occur at almost the same current levels for devices with different channel widths, which is attributed to the parasitic transistors located at the channel width edges. Therefore, we propose that the positive charges trapped at the back-channel interface cause the negative shift, and the origin of the hump is considered as being due to more positive charges trapped at the edges along the channel width direction. On the other hand, the hump-effect becomes more significant in a short channel device （L=2 μm）. It is proposed that the diffusion of oxygen vacancies takes place from the high concentration source/drain region to the intrinsic channel region.
基金supported by the National High-Tech Research and Development Program of China (No. 2004AA303542)
文摘The Indium tin oxide（ITO） thin film possesses excellent photoelectric properties that enable it to act as an ideal transparent conductor.To obtain high-quality ITO films through sol-gel method, the ionic surfactant monoethanolamine and the non-ionic surfactant polyethylene glycol（PEG） were added to the ITO precursor slurry.The influences of surfactants on the structural and photoelectric properties of ITO film samples were investigated.XRD patterns indicated that surfactant monoethanolamine contributed to film predominant grain orientation along the（400） plane.The high transmittance（over 95%） was attributed to the preferred orientation and the grain size expansion of ITO films.SEM showed that the surface particle size and the morphology of ITO films were strongly dependent on the kind of surfactants used.Moving to the shortwave region, the absorption edge of the films exhibited the Burstein-Moss shift.
基金financially supported by the National Natural Science Foundation of China (No.61223002)the State Key Laboratory of Electronic Thin Films and Integrated Devices Foundation of China (No.KFJJ201206)Science and Technology Innovation Foundation of Sichuan (No.2012ZZ020)
文摘Indium tin oxide （ITO） thin films were prepared on alumina ceramic substrates by radio frequency magnetron sputtering. The samples were subsequently annealed in air at temperatures ranging from 500 to 1,100 ℃ for 1 h. The influences of the annealing temperature on the microstructure and electrical properties of the ITO thin films were investigated, and the results indicate that the as-deposited ITO thin films are amorphous in nature. All samples were crystallized by annealing at 500 ~C. As the annealing temperature increases, the predominant orientation shifts from （222） to （400）. The carrier concentration decreases initially and then increases when the annealing temperature rises beyond 1,000 ℃. The resistivity of the ITO thin films increases smoothly as the annealing temperature increases to just below 900 ℃. Beyond 900 ℃, however, the resistivity of the films increases sharply. The annealing temperature has a significant effect on the stability of the ITO/Pt thin film thermocouples （TFTCs）. TFTCs annealed at 1,000 ℃ show improved high- temperature stability and Seebeck coefficients of up to 77.73 pV/℃.
文摘Carbon nanotubes （CNTs） have emerged as an important material for printed macroelectronics. However, achieving printed complementary macroelectronics solely based on CNTs is difficult because it is still challenging to make reliable n-type CNT transistors. In this study, we report threshold voltage （Vth） tuning and printing of complementary transistors and inverters composed of thin films of CNTs and indium zinc oxide （IZO） as p-type and n-type transistors, respectively. We have optimized the Vth of p-type transistors by comparing Ti/Au and Ti/Pd as source/drain electrodes, and observed that CNT transistors with Ti/Au electrodes exhibited enhancement mode operation （Vth 〈 0）. In addition, the optimized In：Zn ratio offers good n-type transistors with high on-state current （Ion） and enhancement mode operation （Vth 〉 0）. For example, an In：Zn ratio of 2：1 yielded an enhancement mode n-type transistor with Vth - 1 V and Ion of 5.2 μA. Furthermore, by printing a CNT thin film and an IZO thin film on the same substrate, we have fabricated a complementary inverter with an output swing of 99.6% of the supply voltage and a voltage gain of 16.9. This work shows the promise of the hybrid integration of p-type CNT and n-type IZO for complementary transistors and circuits.
文摘Niobium-doped indium tin oxide （ITO：Nb） thin films are fabricated on glass substrates by radio frequency （RF） magnetron sputtering at different temperatures. Structural, electrical and optical properties of the films are investigated using X-ray diffraction （XRD）, atomic force microscopy （AFM）, ultraviolet-visible （UV-VIS） spectroscopy and electrical measurements. XRD patterns show that the preferential orientation ofpolycrystalline structure changes from （400） to （222） crystal plane, and the crystallite size increases with the increase of substrate temperature. AFM analyses reveal that the film is very smooth at low temperature. The root mean square （RMS） roughness and the average roughness are 2.16 nm and 1.64 nm, respectively. The obtained lowest resistivity of the films is 1.2 × 10^4 Ω-cm, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 16.5 cmVV.s and 1.88× 10^21 cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which is varied from 3.49 eV to 3.63 eV.
