Carbon nanotube thin film transistor(CNT-TFT) is an emerging technology for future macroelectronics,such as chemical and biological sensors,optical detectors,and the backplane driving circuits for flat panel displays....Carbon nanotube thin film transistor(CNT-TFT) is an emerging technology for future macroelectronics,such as chemical and biological sensors,optical detectors,and the backplane driving circuits for flat panel displays.The mostly reported fabrication method of CNT-TFT is a lift-off based photolithography process.In such fabrication process,photoresist(PR) residue contaminates the interface of tube-metal contact and deteriorates the device performance.In this paper,ultraviolet ozone(UVO) and oxygen plasma treatments were employed to remove the PR contamination.Through our well-designed experiments,the UVO treatment is confirmed an effective way of cleaning contamination at the tube-metal interface,while oxygen plasma treatment is too reactive and hard to control,which is not appropriate for CNT-TFTs.It is determined that 2–6 min UVO treatment is the preferred window,and the best optimized treatment time is 4 min,which leads to 15% enhancement of device performance.展开更多
The time evolution of oxygen plasma treated polystyrene(PS)surfaces was investigated upon storing them in theair under controlled humidity conditions.The methods of water contact angle,X-ray photoelectron spectroscopy...The time evolution of oxygen plasma treated polystyrene(PS)surfaces was investigated upon storing them in theair under controlled humidity conditions.The methods of water contact angle,X-ray photoelectron spectroscopy(XPS),sumfrequency generation(SFG)vibrational spectroscopy,and atomic force microscopy(AFM)were used to infer the surfaceproperties and structure.Chemical groups containing oxygen were formed on the PS surface with the plasma treatment,demonstrated by water contact angle and XPS.The surface polarity decayed markedly on time,as assessed by steady increasein the water contact angle as a function of storage time,from zero to around 60°.The observed decay is interpreted as arisingfrom surface rearrangement processes to burying polar groups away from the uppermost layer of the surfaces,which is incontact with air.On the other hand,XPS results show that the chemical composition in the first 3 nm surface layer isunaffected by the surface aging,and the depth profile of oxygen is essentially the same with time.A possible change of PSsurface roughness was examined by AFM,and it showed that the increase of water contact angle during surface aging couldnot be attributed to surface roughness.Thus,it is concluded that surface aging is attributable to surface reorganization andthe motion of oxygen containing groups is confined within the XPS probing depth.SFG spectroscopy,which is intrinsicallyinterface-specific,was used to detect the chemical structure of PS surface at the molecular level after various aging times.The results are interpreted as follows.During the aging of the plasma treated PS surfaces,the oxygen containing groupsundergo reorientation processes toward the polymer bulk and/or parallel to the surface,while the CH_2 moiety stands up onthe PS surface.Our results indicate that the surface configuration changes do not require large length scale segmentalmotions or migration of macromolecules.Motions that are responsible for surface configuration changes could be relativelysmall rotational motions.The aging behaviors under different relative humidity conditions were shown to be similar from18% to 91%,whereas the kinetics of surface polarity decays were faster in higher relative humidity.Here,the surfacerearrangement of polystyrene films that were previously treated by oxygen plasma and aged,and was investigated in terms ofcontact angle after the water immersion.The contact angles of the water-immersed samples were found to change andapproach the initial values before the immersion asymptotically.展开更多
基金supported by the National Key Research and Development Program of China(2016YFA0201902)the National Natural Science Foundation of China(61621061)Beijing Municipal Science&Technology Commission(Z171100002017001)
文摘Carbon nanotube thin film transistor(CNT-TFT) is an emerging technology for future macroelectronics,such as chemical and biological sensors,optical detectors,and the backplane driving circuits for flat panel displays.The mostly reported fabrication method of CNT-TFT is a lift-off based photolithography process.In such fabrication process,photoresist(PR) residue contaminates the interface of tube-metal contact and deteriorates the device performance.In this paper,ultraviolet ozone(UVO) and oxygen plasma treatments were employed to remove the PR contamination.Through our well-designed experiments,the UVO treatment is confirmed an effective way of cleaning contamination at the tube-metal interface,while oxygen plasma treatment is too reactive and hard to control,which is not appropriate for CNT-TFTs.It is determined that 2–6 min UVO treatment is the preferred window,and the best optimized treatment time is 4 min,which leads to 15% enhancement of device performance.
基金This work was funded in part by NSF(DMR-0084301)Eastman Kodak Company.
文摘The time evolution of oxygen plasma treated polystyrene(PS)surfaces was investigated upon storing them in theair under controlled humidity conditions.The methods of water contact angle,X-ray photoelectron spectroscopy(XPS),sumfrequency generation(SFG)vibrational spectroscopy,and atomic force microscopy(AFM)were used to infer the surfaceproperties and structure.Chemical groups containing oxygen were formed on the PS surface with the plasma treatment,demonstrated by water contact angle and XPS.The surface polarity decayed markedly on time,as assessed by steady increasein the water contact angle as a function of storage time,from zero to around 60°.The observed decay is interpreted as arisingfrom surface rearrangement processes to burying polar groups away from the uppermost layer of the surfaces,which is incontact with air.On the other hand,XPS results show that the chemical composition in the first 3 nm surface layer isunaffected by the surface aging,and the depth profile of oxygen is essentially the same with time.A possible change of PSsurface roughness was examined by AFM,and it showed that the increase of water contact angle during surface aging couldnot be attributed to surface roughness.Thus,it is concluded that surface aging is attributable to surface reorganization andthe motion of oxygen containing groups is confined within the XPS probing depth.SFG spectroscopy,which is intrinsicallyinterface-specific,was used to detect the chemical structure of PS surface at the molecular level after various aging times.The results are interpreted as follows.During the aging of the plasma treated PS surfaces,the oxygen containing groupsundergo reorientation processes toward the polymer bulk and/or parallel to the surface,while the CH_2 moiety stands up onthe PS surface.Our results indicate that the surface configuration changes do not require large length scale segmentalmotions or migration of macromolecules.Motions that are responsible for surface configuration changes could be relativelysmall rotational motions.The aging behaviors under different relative humidity conditions were shown to be similar from18% to 91%,whereas the kinetics of surface polarity decays were faster in higher relative humidity.Here,the surfacerearrangement of polystyrene films that were previously treated by oxygen plasma and aged,and was investigated in terms ofcontact angle after the water immersion.The contact angles of the water-immersed samples were found to change andapproach the initial values before the immersion asymptotically.
