The negative gate bias stress(NBS)reliability of n-type polycrystalline silicon(poly-Si)thin-film transistors(TFTs)with a distinct defective grain boundary(GB)in the channel is investigated.Results show that conventio...The negative gate bias stress(NBS)reliability of n-type polycrystalline silicon(poly-Si)thin-film transistors(TFTs)with a distinct defective grain boundary(GB)in the channel is investigated.Results show that conventional NBS degradation with negative shift of the transfer curves is absent.The on-state current is decreased,but the subthreshold characteristics are not affected.The gate bias dependence of the drain leakage current at V_(ds)of 5.0 V is suppressed,whereas the drain leakage current at V_(ds)of 0.1 V exhibits obvious gate bias dependence.As confirmed via TCAD simulation,the corresponding mechanisms are proposed to be trap state generation in the GB region,positive-charge local formation in the gate oxide near the source and drain,and trap state introduction in the gate oxide.展开更多
A new type of degradation phenomena featured with increased subthreshold swing and threshold voltage after negative gate bias stress(NBS)is observed for amorphous InGaZnO(a-IGZO)thin-film transistors(TFTs),which can r...A new type of degradation phenomena featured with increased subthreshold swing and threshold voltage after negative gate bias stress(NBS)is observed for amorphous InGaZnO(a-IGZO)thin-film transistors(TFTs),which can recover in a short time.After comparing with the degradation phenomena under negative bias illumination stress(NBIS),positive bias stress(PBS),and positive bias illumination stress(PBIS),degradation mechanisms under NBS is proposed to be the generation of singly charged oxygen vacancies(V_(o)^(+))in addition to the commonly reported doubly charged oxygen vacancies(V_(o)^(2+)).Furthermore,the NBS degradation phenomena can only be observed when the transfer curves after NBS are measured from the negative gate bias to the positive gate bias direction due to the fast recovery of V_(o)^(+)under positive gate bias.The proposed degradation mechanisms are verified by TCAD simulation.展开更多
The evolution and the origin of“solid-like state”in molten polymer/clay nanocomposites are studied.Usingpolypropylene/clay hybrid(PPCH)with sufficient maleic anhydride modified PP(PP-MA)as compatibilizer,well exfoli...The evolution and the origin of“solid-like state”in molten polymer/clay nanocomposites are studied.Usingpolypropylene/clay hybrid(PPCH)with sufficient maleic anhydride modified PP(PP-MA)as compatibilizer,well exfoliationyet solid-like state was achieved after annealing in molten state.Comprehensive linear viscoelasticity and non-lineartheological behaviors together with WAXD and TEM are studied on PPCH at various dispersion stages focusing on time,temperature and deformation dependencies of the“solid-like”state in molten nanocomposites.Based on these,it is revealedthat the solid-structure is developed gradually along with annealing through the stages of inter-layer expansion by PP-MA,the diffusion and association of exfoliated silicate platelets,the formation of band/chain structure and,finally,a percolatedclay associated network,which is responsible for the melt rigidity or solid-like state.The network will be broken down bymelt frozen/crystallization and weakened at large shear or strong flow and,even more surprisingly,may be disrupted by usingtrace amount of silane coupling agent which may block the edge interaction of platelets.The solid-like structure causescharacteristic non-linear rheological behaviors,e.g.residual stress after step shear,abnormal huge stress overshoots in stepflows and,most remarkably,the negative first normal stress functions in steady shear or step flows.The rheological andstructural arguments challenge the existing models of strengthened entangled polymer network by tethered polymer chainsconnecting clay particles or by chains in confined melts or frictional interaction among tactoids.A scheme of percolatednetworking of associated clay platelets,which may in band form of edge connecting exfoliated platelets,is suggested toexplain previous experimental results.展开更多
The structure and rheological properties of carbon-based particle suspensions, i.e., carbon black(CB), multi-wall carbon nanotube(MWNT), graphene and hollow carbon sphere(HCS) suspended in polydimethylsiloxane(...The structure and rheological properties of carbon-based particle suspensions, i.e., carbon black(CB), multi-wall carbon nanotube(MWNT), graphene and hollow carbon sphere(HCS) suspended in polydimethylsiloxane(PDMS), are investigated. In order to study the effect of particle shape on the structure and rheological properties of suspensions, the content of surface oxygen-containing functional groups of carbon-based particles is controlled to be similar. Original spherical-like CB(fractal filler), rod-like MWNT and sheet-like graphene form large agglomerates in PDMS, while spherical HCS particles disperse relatively well in PDMS. The dispersion state of carbon-based particles affects the critical concentration of forming a rheological percolation network. Under weak shear, negative normal stress differences(ΔN) are observed in CB, MWNT and graphene suspensions, while ΔN is nearly zero for HCS suspensions. It is concluded that the vorticity alignment of CB, MWNT and graphene agglomerates under shear results in the negative ΔN. However, no obvious structural change is observed in HCS suspension under weak shear, and accordingly, the ΔN is almost zero.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61971299 and 61974101)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20201201)+1 种基金the Fund from Suzhou Science and Technology Bureau(Grant No.SYG201933)the Fund from the State Key Laboratory of ASIC and System,Fudan University(Grant No.2021KF005)
文摘The negative gate bias stress(NBS)reliability of n-type polycrystalline silicon(poly-Si)thin-film transistors(TFTs)with a distinct defective grain boundary(GB)in the channel is investigated.Results show that conventional NBS degradation with negative shift of the transfer curves is absent.The on-state current is decreased,but the subthreshold characteristics are not affected.The gate bias dependence of the drain leakage current at V_(ds)of 5.0 V is suppressed,whereas the drain leakage current at V_(ds)of 0.1 V exhibits obvious gate bias dependence.As confirmed via TCAD simulation,the corresponding mechanisms are proposed to be trap state generation in the GB region,positive-charge local formation in the gate oxide near the source and drain,and trap state introduction in the gate oxide.
基金Project supported in part by the National Natural Science Foundation of China(Grant Nos.61971299 and 61974101)the Natural Science Foundation of Jiangsu Province,China(Grant No.SBK2020021406)+2 种基金the Fund from the State Key Laboratory of ASIC and System,Fudan University(Grant No.2019KF007)the Fund from the Suzhou Science and Technology Bureau(Grant No.SYG201933)the Fund from the Jiangsu Higher Education Institute of China(Grant No.19KJB510058).
文摘A new type of degradation phenomena featured with increased subthreshold swing and threshold voltage after negative gate bias stress(NBS)is observed for amorphous InGaZnO(a-IGZO)thin-film transistors(TFTs),which can recover in a short time.After comparing with the degradation phenomena under negative bias illumination stress(NBIS),positive bias stress(PBS),and positive bias illumination stress(PBIS),degradation mechanisms under NBS is proposed to be the generation of singly charged oxygen vacancies(V_(o)^(+))in addition to the commonly reported doubly charged oxygen vacancies(V_(o)^(2+)).Furthermore,the NBS degradation phenomena can only be observed when the transfer curves after NBS are measured from the negative gate bias to the positive gate bias direction due to the fast recovery of V_(o)^(+)under positive gate bias.The proposed degradation mechanisms are verified by TCAD simulation.
基金This work was funded by the NSFC of China(No.20490220)Major State Basic Research Projects(2003CB615604)SINOPEC Petrochemical Co.Ltd.(Project X501029).
文摘The evolution and the origin of“solid-like state”in molten polymer/clay nanocomposites are studied.Usingpolypropylene/clay hybrid(PPCH)with sufficient maleic anhydride modified PP(PP-MA)as compatibilizer,well exfoliationyet solid-like state was achieved after annealing in molten state.Comprehensive linear viscoelasticity and non-lineartheological behaviors together with WAXD and TEM are studied on PPCH at various dispersion stages focusing on time,temperature and deformation dependencies of the“solid-like”state in molten nanocomposites.Based on these,it is revealedthat the solid-structure is developed gradually along with annealing through the stages of inter-layer expansion by PP-MA,the diffusion and association of exfoliated silicate platelets,the formation of band/chain structure and,finally,a percolatedclay associated network,which is responsible for the melt rigidity or solid-like state.The network will be broken down bymelt frozen/crystallization and weakened at large shear or strong flow and,even more surprisingly,may be disrupted by usingtrace amount of silane coupling agent which may block the edge interaction of platelets.The solid-like structure causescharacteristic non-linear rheological behaviors,e.g.residual stress after step shear,abnormal huge stress overshoots in stepflows and,most remarkably,the negative first normal stress functions in steady shear or step flows.The rheological andstructural arguments challenge the existing models of strengthened entangled polymer network by tethered polymer chainsconnecting clay particles or by chains in confined melts or frictional interaction among tactoids.A scheme of percolatednetworking of associated clay platelets,which may in band form of edge connecting exfoliated platelets,is suggested toexplain previous experimental results.
基金financially supported by the National Natural Science Foundation of China(Nos.21474111,21222407 and 21274152)subsidized by the National Basic Research Program of China(973 Program,2012CB821500)
文摘The structure and rheological properties of carbon-based particle suspensions, i.e., carbon black(CB), multi-wall carbon nanotube(MWNT), graphene and hollow carbon sphere(HCS) suspended in polydimethylsiloxane(PDMS), are investigated. In order to study the effect of particle shape on the structure and rheological properties of suspensions, the content of surface oxygen-containing functional groups of carbon-based particles is controlled to be similar. Original spherical-like CB(fractal filler), rod-like MWNT and sheet-like graphene form large agglomerates in PDMS, while spherical HCS particles disperse relatively well in PDMS. The dispersion state of carbon-based particles affects the critical concentration of forming a rheological percolation network. Under weak shear, negative normal stress differences(ΔN) are observed in CB, MWNT and graphene suspensions, while ΔN is nearly zero for HCS suspensions. It is concluded that the vorticity alignment of CB, MWNT and graphene agglomerates under shear results in the negative ΔN. However, no obvious structural change is observed in HCS suspension under weak shear, and accordingly, the ΔN is almost zero.