Amorphous indium-gallium-zinc oxide(a-IGZO)thin films are prepared by pulsed laser deposition and fabricated into thin-film transistor(TFT)devices.In-situ x-ray photoelectron spectroscopy(XPS)illustrates that weakly b...Amorphous indium-gallium-zinc oxide(a-IGZO)thin films are prepared by pulsed laser deposition and fabricated into thin-film transistor(TFT)devices.In-situ x-ray photoelectron spectroscopy(XPS)illustrates that weakly bonded oxygen(O)atoms exist in a-IGZO thin films deposited at high O_(2) pressures,but these can be eliminated by vacuum annealing.The threshold voltage(V_(th))of the a-IGZO TFTs is shifted under positive gate bias,and the Vth shift is positively related to the deposition pressure.A temperature variation experiment in the range of 20 K-300 K demonstrates that an activation energy of 144 meV is required for the Vth shift,which is close to the activation energy required for the migration of weakly bonded O atoms in a-IGZO thin films.Accordingly,the Vth shift is attributed to the acceptor-like states induced by the accumulation of weakly bonded O atoms at the a-IGZO/SiO_(2) interface under positive gate bias.These results provide an insight into the mechanism responsible for the Vth shift of the a-IGZO TFTs and help in the production of reliable designs.展开更多
Ring oscillators based on indium gallium zinc oxide thin film transistors are fabricated on glass substrates. The oscillator circuit consists of seven delay stages and an output buffer inverter. The element inverter e...Ring oscillators based on indium gallium zinc oxide thin film transistors are fabricated on glass substrates. The oscillator circuit consists of seven delay stages and an output buffer inverter. The element inverter exhibits a voltage gain higher than -6 V/V and a wide output swing close to 85% of the full swing range. The dynamic performance of the ring oscillators is evaluated as a function of supply voltage and at different gate lengths. A maximum oscillation frequency of 0.88MHz is obtained for a supply voltage of 50V, corresponding to a propagation delay of less than 85 ns/stage.展开更多
In this paper, ATLAS 2D device simulator of SILVACO was used for device simulation of inverted- staggered thin film transistor using amorphous indium gallium zinc oxide as active layer （a-IGZO-TFT） with double activ...In this paper, ATLAS 2D device simulator of SILVACO was used for device simulation of inverted- staggered thin film transistor using amorphous indium gallium zinc oxide as active layer （a-IGZO-TFT） with double active layers, based on the density of states （DOS） model of amorphous material. The change of device performance induced by the thickness variation of each active layer was studied, and the interface between double active layers was analyzed. The best performance was found when the interface was near the edge of the channel, by optimizing the thickness of each active layers, the high performance device of threshold voltage （Vth） = -0.89 V, sub-threshold swing （SS）= 0.27, on/off current ratio （IoN/IoFF） = 6.98 × 10^14 was obtained.展开更多
Transparent oxide semiconductor, a-IGZO, thin films were prepared by high-vacuum RF magnetron sputtering at different working pressures. The effect of working pressure on crystal structure, surface morphology, and ele...Transparent oxide semiconductor, a-IGZO, thin films were prepared by high-vacuum RF magnetron sputtering at different working pressures. The effect of working pressure on crystal structure, surface morphology, and electrical and optical properties of the films was studied. The highest ball mobility of 17.45 cmZ-V-l.s- 1 is obtained at 0.3 Pa with annealing at 200 ℃, while the highest carrier concentration of 2.32×10^20 cm^-3 and the lowest resistivity of 0.001568 Ω.cm are obtained at 0.45 Pa with annealing. The highest transmittance of 90.9 % is obtained at 0.9 Pa with annealing treatment. A ＂blue shift＂ of UV absorption edge is observed with the increase of working press ure.展开更多
We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode...We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore,good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.展开更多
Photodetectors based on amorphous InGaZnO(a-IGZO)thin film transistor(TFT)and halide perovskites have attracted attention in recent years.However,such a stack assembly of a halide perovskite layer/an a-IGZO channel,ev...Photodetectors based on amorphous InGaZnO(a-IGZO)thin film transistor(TFT)and halide perovskites have attracted attention in recent years.However,such a stack assembly of a halide perovskite layer/an a-IGZO channel,even with an organic semiconductor film inserted between them,easily has a very limited photoresponsivity.In this article,we investigate photoresponsive characteristics of TFTs by using CsPbX3(X=Br or I)quantum dots(QDs)embedded into the a-IGZO channel,and attain a high photoresponsivity over 10^3A·W^-1,an excellent detectivity in the order of 10^16 Jones,and a light-to-dark current ratio up to 10^5 under visible lights.This should be mainly attributed to the improved transfer efficiency of photoelectrons from the QDs to the a-IGZO channel.Moreover,spectrally selective photodetection is demonstrated by introducing halide perovskite QDs with different bandgaps.Thus,this work provides a novel strategy of device structure optimization for significantly improving the photoresponsive characteristics of TFT photodetectors.展开更多
Degradation of a-InGaZnO thin-film transistors working under simultaneous DC gate and drain bias stress is investigated,and the corresponding degradation mechanism is proposed and verified.The maximum degradation occu...Degradation of a-InGaZnO thin-film transistors working under simultaneous DC gate and drain bias stress is investigated,and the corresponding degradation mechanism is proposed and verified.The maximum degradation occurs under the bias stress condition that makes the electric field and electron concentration relatively high at the same time.Trapping of hot electrons in the etching-stop layer under the extended drain electrode is proven to be the underlying mechanism.The observed degradation phenomena,including distortion in the transfer curve on a logarithmic scale and two-slope dependence on gate bias on a linear scale,current crowding in the output curve,and smaller degradation in transfer curves measured under large drain bias,can all be well explained with the proposed degradation mechanism.展开更多
As growing applications demand higher driving currents of oxide semiconductor thin-film transistors(TFTs),severe instabilities and even hard breakdown under high-current stress(HCS)become critical challenges.In this w...As growing applications demand higher driving currents of oxide semiconductor thin-film transistors(TFTs),severe instabilities and even hard breakdown under high-current stress(HCS)become critical challenges.In this work,the triggering voltage of HCS-induced self-heating(SH)degradation is defined in the output characteristics of amorphous indium-galliumzinc oxide(a-IGZO)TFTs,and used to quantitatively evaluate the thermal generation process of channel donor defects.The fluorinated a-IGZO(a-IGZO:F)was adopted to effectively retard the triggering of the self-heating(SH)effect,and was supposed to originate from the less population of initial deep-state defects and a slower rate of thermal defect transition in a-IGZO:F.The proposed scheme noticeably enhances the high-current applications of oxide TFTs.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51771144 and 62104189)the Natural Science Foundation of Shaanxi Province,China(Grant Nos.2021JC-06,2019TD-020,and 2019JLM-30)+1 种基金the China Postdoctoral Science Foundation(Grant No.2020M683483)the Fundamental scientific research business expenses of Xi'an Jiaotong University(Grant No.XZY022020017).
文摘Amorphous indium-gallium-zinc oxide(a-IGZO)thin films are prepared by pulsed laser deposition and fabricated into thin-film transistor(TFT)devices.In-situ x-ray photoelectron spectroscopy(XPS)illustrates that weakly bonded oxygen(O)atoms exist in a-IGZO thin films deposited at high O_(2) pressures,but these can be eliminated by vacuum annealing.The threshold voltage(V_(th))of the a-IGZO TFTs is shifted under positive gate bias,and the Vth shift is positively related to the deposition pressure.A temperature variation experiment in the range of 20 K-300 K demonstrates that an activation energy of 144 meV is required for the Vth shift,which is close to the activation energy required for the migration of weakly bonded O atoms in a-IGZO thin films.Accordingly,the Vth shift is attributed to the acceptor-like states induced by the accumulation of weakly bonded O atoms at the a-IGZO/SiO_(2) interface under positive gate bias.These results provide an insight into the mechanism responsible for the Vth shift of the a-IGZO TFTs and help in the production of reliable designs.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CB301900 and 2011CB922100the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Ring oscillators based on indium gallium zinc oxide thin film transistors are fabricated on glass substrates. The oscillator circuit consists of seven delay stages and an output buffer inverter. The element inverter exhibits a voltage gain higher than -6 V/V and a wide output swing close to 85% of the full swing range. The dynamic performance of the ring oscillators is evaluated as a function of supply voltage and at different gate lengths. A maximum oscillation frequency of 0.88MHz is obtained for a supply voltage of 50V, corresponding to a propagation delay of less than 85 ns/stage.
文摘In this paper, ATLAS 2D device simulator of SILVACO was used for device simulation of inverted- staggered thin film transistor using amorphous indium gallium zinc oxide as active layer （a-IGZO-TFT） with double active layers, based on the density of states （DOS） model of amorphous material. The change of device performance induced by the thickness variation of each active layer was studied, and the interface between double active layers was analyzed. The best performance was found when the interface was near the edge of the channel, by optimizing the thickness of each active layers, the high performance device of threshold voltage （Vth） = -0.89 V, sub-threshold swing （SS）= 0.27, on/off current ratio （IoN/IoFF） = 6.98 × 10^14 was obtained.
基金financially supported by the National Natural Science Foundation of China (No. 51571010)
文摘Transparent oxide semiconductor, a-IGZO, thin films were prepared by high-vacuum RF magnetron sputtering at different working pressures. The effect of working pressure on crystal structure, surface morphology, and electrical and optical properties of the films was studied. The highest ball mobility of 17.45 cmZ-V-l.s- 1 is obtained at 0.3 Pa with annealing at 200 ℃, while the highest carrier concentration of 2.32×10^20 cm^-3 and the lowest resistivity of 0.001568 Ω.cm are obtained at 0.45 Pa with annealing. The highest transmittance of 90.9 % is obtained at 0.9 Pa with annealing treatment. A ＂blue shift＂ of UV absorption edge is observed with the increase of working press ure.
文摘We report a high-performance active image sensor pixel design by utilizing amorphous-indium-gallium-zinc-oxide(aIGZO) thin-film transistors(TFTs) with a circular structure. The TFT, configured with the inner electrode as source and outer electrode as drain, typically exhibits good saturation electrical characteristics, where the device has a constant drive current despite variations in drain voltage. Due to the very high output resistance exhibited by this asymmetric TFT structure with a circular shape, the pixel circuit considered here in common-drain configuration provides a higher gain of operation than a pixel circuit implemented with rectangular a-IGZO TFTs. They can be used as driving TFTs in active image sensor circuits. They are, therefore,good candidates for digital X-ray detectors in applications such as medical diagnostic procedures.
基金Project supported by the National Natural Science Foundation of China(Grant No.61874029)the National Key Technologies R&D Program of China(Grant No.2015ZX02102-003).
文摘Photodetectors based on amorphous InGaZnO(a-IGZO)thin film transistor(TFT)and halide perovskites have attracted attention in recent years.However,such a stack assembly of a halide perovskite layer/an a-IGZO channel,even with an organic semiconductor film inserted between them,easily has a very limited photoresponsivity.In this article,we investigate photoresponsive characteristics of TFTs by using CsPbX3(X=Br or I)quantum dots(QDs)embedded into the a-IGZO channel,and attain a high photoresponsivity over 10^3A·W^-1,an excellent detectivity in the order of 10^16 Jones,and a light-to-dark current ratio up to 10^5 under visible lights.This should be mainly attributed to the improved transfer efficiency of photoelectrons from the QDs to the a-IGZO channel.Moreover,spectrally selective photodetection is demonstrated by introducing halide perovskite QDs with different bandgaps.Thus,this work provides a novel strategy of device structure optimization for significantly improving the photoresponsive characteristics of TFT photodetectors.
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Degradation of a-InGaZnO thin-film transistors working under simultaneous DC gate and drain bias stress is investigated,and the corresponding degradation mechanism is proposed and verified.The maximum degradation occurs under the bias stress condition that makes the electric field and electron concentration relatively high at the same time.Trapping of hot electrons in the etching-stop layer under the extended drain electrode is proven to be the underlying mechanism.The observed degradation phenomena,including distortion in the transfer curve on a logarithmic scale and two-slope dependence on gate bias on a linear scale,current crowding in the output curve,and smaller degradation in transfer curves measured under large drain bias,can all be well explained with the proposed degradation mechanism.
基金supported by National Key Research and Development Program under Grant No.2022YFB3607100Shenzhen Research Programs under Grant Nos.JCYJ20200109140601691,JCYJ20190808154803565,SGDX20201103095607022,SGDX20211123145404006,and GXWD20201231165807007-20200807025846001。
文摘As growing applications demand higher driving currents of oxide semiconductor thin-film transistors(TFTs),severe instabilities and even hard breakdown under high-current stress(HCS)become critical challenges.In this work,the triggering voltage of HCS-induced self-heating(SH)degradation is defined in the output characteristics of amorphous indium-galliumzinc oxide(a-IGZO)TFTs,and used to quantitatively evaluate the thermal generation process of channel donor defects.The fluorinated a-IGZO(a-IGZO:F)was adopted to effectively retard the triggering of the self-heating(SH)effect,and was supposed to originate from the less population of initial deep-state defects and a slower rate of thermal defect transition in a-IGZO:F.The proposed scheme noticeably enhances the high-current applications of oxide TFTs.
