Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and ...Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.展开更多
In this manuscript,the perovskite-based metal–oxide–semiconductor field effect transistors（MOSFETs） with phenylC61-butyric acid methylester（PCBM） layers are studied.The MOSFETs are fabricated on perovskites,and ...In this manuscript,the perovskite-based metal–oxide–semiconductor field effect transistors（MOSFETs） with phenylC61-butyric acid methylester（PCBM） layers are studied.The MOSFETs are fabricated on perovskites,and characterized by photoluminescence spectra（PL）,x-ray diffraction（XRD）,and x-ray photoelectron spectroscopy（XPS）.With PCBM layers,the current–voltage hysteresis phenomenon is effetely inhibited,and both the transfer and output current values increase.The band energy diagrams are proposed,which indicate that the electrons are transferred into the PCBM layer,resulting in the increase of photocurrent.The electron mobility and hole mobility are extracted from the transfer curves,which are about one order of magnitude as large as those of PCBM deposited,which is the reason why the electrons are transferred into the PCBM layer and the holes are still in the perovskites,and the effects of ionized impurity scattering on carrier transport become smaller.展开更多
A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferr...A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-Tr FE)). We overcame the interfacial layer problem by incorporating P(VDF-Tr FE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 105, a long retention time greater than 3 9 104 s, and a high endurance of over 105 programming cycles while maintaining an ION/IOFFratio higher than 102.展开更多
The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is o...The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is of great importance not only to device physics but also to technological applications. Here we demonstrate a widely tunable bandgap of few-layer black phosphorus （BP） by the application of vertical electric field in dual-gated BP field-effect transistors. A total bandgap reduction of 124 meV is observed when the electrical displacement field is increased from 0.10 V/nm to 0.83 V/nm. Our results suggest appealing potential for few-layer BP as a tunable bandgap material in infrared optoelectronies, thermoelectric power generation and thermal imaging.展开更多
Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero...Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.展开更多
Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and requi...Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.展开更多
A vertical carbon nanotube field-effect transistor(CNTFET) based on silicon(Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube(SWNT) and an n-type Si nanowire ...A vertical carbon nanotube field-effect transistor(CNTFET) based on silicon(Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube(SWNT) and an n-type Si nanowire in series construct the channel of the transistor. The CNTFET presents ambipolar characteristics at positive drain voltage(Vd) and n-type characteristics at negative Vd. The current is significantly influenced by the doping level of n-Si and the SWNT band gap. The n-branch current of the ambipolar characteristics increases with increasing doping level of the n-Si while the p-branch current decreases. The SWNT band gap has the same influence on the p-branch current at a positive Vd and n-type characteristics at negative Vd. The lower the SWNT band gap, the higher the current. However, it has no impact on the n-branch current in the ambipolar characteristics. Thick oxide is found to significantly degrade the current and the subthreshold slope of the CNTFETs.展开更多
Various biaxial compressive strained GaSb p-channel metal-oxide-semiconductor field-effect transistors （MOSFETs） are experimentally and theoretically investigated, The biaxial compressive strained GaSb MOSFETs show ...Various biaxial compressive strained GaSb p-channel metal-oxide-semiconductor field-effect transistors （MOSFETs） are experimentally and theoretically investigated, The biaxial compressive strained GaSb MOSFETs show a high peak mobility of 638 cm2/V.s, which is 3.86 times of the extracted mobility of the fabricated GaSb MOSFETs without strain. Meanwhile, first principles calculations show that the hole effective mass of GaSb depends on the biaxial compressive strain. The biaxiai compressive strain brings a remarkable enhancement of the hole mobility caused by a significant reduction in the hole effective mass due to the modulation of the valence bands.展开更多
Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as a...Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as an option for conventional silicon devices. As a critical step in the design cycle of modem IC products, compact model refers to the development of models for integrated semiconductor devices for use in circuit simulations. The purpose of this review is to provide a theoretical description of current compact model of graphene field-effect transistors. Special attention is devoted to the charge sheet model, drift-diffusion model, Boltzmann equation, density of states （DOS）, and surface-potential-based compact model. Finally, an outlook of this field is briefly discussed.展开更多
We present the design consideration and fabrication of 4H-SiC trenched-and-implanted vertical junction field-effect transistors （TI-VJFETs）. Different design factors, including channel width, channel doping, and mes...We present the design consideration and fabrication of 4H-SiC trenched-and-implanted vertical junction field-effect transistors （TI-VJFETs）. Different design factors, including channel width, channel doping, and mesa height, are con- sidered and evaluated by numerical simulations. Based on the simulation result, normally-on and normally-off devices are fabricated. The fabricated device has a 12 μm thick drift layer with 8 × 10^15 cm^-3 N-type doping and 2.6 μm channel length. The normally-on device shows a 1.2 kV blocking capability with a minimum on-state resistance of 2.33 mΩ.cm2, while the normally-off device shows an on-state resistance of 3.85 mΩ.cm2. Both the on-state and the blocking performances of the device are close to the state-of-the-art values in this voltage range.展开更多
In this paper, TiN/A1Ox gated A1GaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors （MOS- HFETs） were fabricated for gate-first process evaluation. By employing a low temperature ohmic process...In this paper, TiN/A1Ox gated A1GaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors （MOS- HFETs） were fabricated for gate-first process evaluation. By employing a low temperature ohmic process, ohmic contact can be obtained by annealing at 600 ℃ with the contact resistance approximately 1.6 Ω.mm. The ohmic annealing process also acts as a post-deposition annealing on the oxide film, resulting in good device performance. Those results demonstrated that the TiN/A1Ox gated MOS-HFETs with low temperature ohmic process can be applied for self-aligned gate AIGaN/GaN MOS-HFETs.展开更多
This paper proposes an effective method of fabricating top contact organic field effect transistors by using a pho- tolithographic process. The semiconductor layer is protected by a passivation layer. Through photolit...This paper proposes an effective method of fabricating top contact organic field effect transistors by using a pho- tolithographic process. The semiconductor layer is protected by a passivation layer. Through photolithographic and etching processes, parts of the passivation layer are etched off to form source/drain electrode patterns. Combined with conventional evaporation and lift-off techniques, organic field effect transistors with a top contact are fabricated suc- cessfully, whose properties are comparable to those prepared with the shadow mask method and one order of magnitude higher than the bottom contact devices fabricated by using a photolithographic process.展开更多
We report a novel structure of A1GaN/GaN heterostructure field effect transistors （HFETs） with a Si and Mg pair- doped interlayer grown on Si substrate. By optimizing the doping concentrations of the pair-doped inte...We report a novel structure of A1GaN/GaN heterostructure field effect transistors （HFETs） with a Si and Mg pair- doped interlayer grown on Si substrate. By optimizing the doping concentrations of the pair-doped interlayers, the mobility of 2DEG increases by twice for the conventional structure under 5 K due to the improved crystalline quality of the conduction channel. The proposed HFET shows a four orders lower off-state leakage current, resulting in a much higher on/off ratio （ - 10^9）. Further temperature-dependent performance of Schottky diodes revealed that the inhibition of shallow surface traps in proposed HFETs should be the main reason for the suppression of leakage current.展开更多
A simple and effective approach to improve the switching characteristics of AlGaN/AlN/GaN heterostructure field effect transistors （HFETs） by applying a voltage bias on the substrate is presented. With the increase ...A simple and effective approach to improve the switching characteristics of AlGaN/AlN/GaN heterostructure field effect transistors （HFETs） by applying a voltage bias on the substrate is presented. With the increase of the substrate bias, the OFF-state drain current is much reduced and the ON-state current keeps constant. Both the ON/OFF current ratio and the subthreshold swing are demonstrated to be greatly improved. With the thinned substrate, the improvement of the switching characteristics with the substrate bias is found to be even greater. The above improvements of the switching characteristics are attributed to the interaction between the substrate bias induced electrical field and the bulk traps in the GaN buffer layer, which reduces the conductivity of the GaN buffer layer.展开更多
An analytical model of gate-all-around （GAA） silicon nanowire tunneling field effect transistors （NW-TFETs） is developted based on the surface potential solutions in the channel direction and considering the band ...An analytical model of gate-all-around （GAA） silicon nanowire tunneling field effect transistors （NW-TFETs） is developted based on the surface potential solutions in the channel direction and considering the band to band tunneling （BTBT） efficiency. The three-dimensional Poisson equation is solved to obtain the surface potential distributions in the partition regions along the channel direction for the NW-TFET, and a tunneling current model using Kane＇s expression is developed. The validity of the developed model is shown by the good agreement between the model predictions and the TCAD simulation results.展开更多
The luminescence intensity regulation of organic light-emitting transistor(OLED)device can be achieved effectively by the combination of graphene vertical field effect transistor(GVFET)and OLED.In this paper,we fabric...The luminescence intensity regulation of organic light-emitting transistor(OLED)device can be achieved effectively by the combination of graphene vertical field effect transistor(GVFET)and OLED.In this paper,we fabricate and characterize the graphene vertical field-effect transistor with gate dielectric of ion-gel film,confirming that its current switching ratio reaches up to 102.Because of the property of high light transmittance in ion-gel film,the OLED device prepared with graphene/PEDOT:PSS as composite anode exhibits good optical properties.We also prepare the graphene vertical organic light-emitting field effect transistor(GVOLEFET)by the combination of GVFET and graphene OLED,analyzing its electrical and optical properties,and confirming that the luminescence intensity can be significantly changed by regulating the gate voltage.展开更多
Nanowires with gate-all-around(GAA) structures are widely considered as the most promising candidate for 3-nm technology with the best ability of suppressing the short channel effects,and tunneling field effect transi...Nanowires with gate-all-around(GAA) structures are widely considered as the most promising candidate for 3-nm technology with the best ability of suppressing the short channel effects,and tunneling field effect transistors(TFETs)based on GAA structures also present improved performance.In this paper,a non-quasi-static(NQS) device model is developed for nanowire GAA TFETs.The model can predict the transient current and capacitance varying with operation frequency,which is beyond the ability of the quasi-static(QS) model published before.Excellent agreements between the model results and numerical simulations are obtained.Moreover,the NQS model is derived from the published QS model including the current-voltage(I-V) and capacitance-voltage(C-V) characteristics.Therefore,the NQS model is compatible with the QS model for giving comprehensive understanding of GAA TFETs and would be helpful for further study of TFET circuits based on nanowire GAA structure.展开更多
Negative Bias Temperature Instability （NBTI） has become one of the most serious reliability problems of metaloxide-semiconductor field-effect transistors （MOSFETs）. The degradation mechanism and model of NBTI are ...Negative Bias Temperature Instability （NBTI） has become one of the most serious reliability problems of metaloxide-semiconductor field-effect transistors （MOSFETs）. The degradation mechanism and model of NBTI are studied in this paper. From the experimental results, the exponential value 0.25-0.5 which represents the relation of NBTI degradation and stress time is obtained. Based on the experimental results and existing model, the reaction-diffusion model with H^＋ related species generated is deduced, and the exponent 0.5 is obtained. The results suggest that there should be H^＋ generated in the NBTI degradation. With the real time method, the degradation with an exponent 0.5 appears clearly in drain current shift during the first seconds of stress and then verifies that H^＋ generated during NBTI stress.展开更多
Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is...Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is present in the transfer characteristics of InGaN/AIGaN/AIN/GaN HFETs. The theoretical calculation shows the coexistence of two-dimensional electron gas （2DEG） and two-dimensional hole gas （2DHG） in InGaN/AIGaN/A1N/GaN heterostructures, and the screening effect of 2DHG to the 2DEG in the conduction channel can explain this current plateau. Moreover, the current plateau shows the time-dependent behavior when IDs Vcs scans repeated are conducted. The obtained insight provides indication for the design in the fabrication of GaN-based super HFETs.展开更多
Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low...Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types： in-plane and vertical heterostructures composed of two kinds of layered phosphorous（β-P and δ-P） by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio（PVR）when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing（SS） of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774019,51572033,and 51572241)the Beijing Municipal Commission of Science and Technology,China(Grant No.SX2018-04)
文摘Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.
基金Project supported by the National Natural Science Foundation of China(Grant No.51602241)the China Postdoctoral Science Foundation(Grant No.2016M592754)
文摘In this manuscript,the perovskite-based metal–oxide–semiconductor field effect transistors（MOSFETs） with phenylC61-butyric acid methylester（PCBM） layers are studied.The MOSFETs are fabricated on perovskites,and characterized by photoluminescence spectra（PL）,x-ray diffraction（XRD）,and x-ray photoelectron spectroscopy（XPS）.With PCBM layers,the current–voltage hysteresis phenomenon is effetely inhibited,and both the transfer and output current values increase.The band energy diagrams are proposed,which indicate that the electrons are transferred into the PCBM layer,resulting in the increase of photocurrent.The electron mobility and hole mobility are extracted from the transfer curves,which are about one order of magnitude as large as those of PCBM deposited,which is the reason why the electrons are transferred into the PCBM layer and the holes are still in the perovskites,and the effects of ionized impurity scattering on carrier transport become smaller.
基金supported by Center for BioNano Health-Guardfunded by the Ministry of Science, ICT & Future Planning (MSIP) of Korea as a Global Frontier Project (HGUARD_2013M3A6B2)
文摘A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped gate organic ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-Tr FE)). We overcame the interfacial layer problem by incorporating P(VDF-Tr FE) as a ferroelectric gate using a low-temperature fabrication process. Our memory devices exhibited excellent memory characteristics with a low programming voltage of ±5 V, a large modulation in channel conductance between ON and OFF states exceeding 105, a long retention time greater than 3 9 104 s, and a high endurance of over 105 programming cycles while maintaining an ION/IOFFratio higher than 102.
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB921900 and 2014CB920900the National Natural Science Foundation of China under Grant No 11374021)(S.Yan,Z.Xie,J.-H,Chen)+1 种基金support from the Elemental Strategy Initiative conducted by the MEXT,Japana Grant-in-Aid for Scientific Research on Innovative Areas"Science of Atomic Layers"from JSPS
文摘The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is of great importance not only to device physics but also to technological applications. Here we demonstrate a widely tunable bandgap of few-layer black phosphorus （BP） by the application of vertical electric field in dual-gated BP field-effect transistors. A total bandgap reduction of 124 meV is observed when the electrical displacement field is increased from 0.10 V/nm to 0.83 V/nm. Our results suggest appealing potential for few-layer BP as a tunable bandgap material in infrared optoelectronies, thermoelectric power generation and thermal imaging.
基金funded by Australian Research Council discovery project DP140103041Future Fellowship FT160100205
文摘Two-dimensional(2D) materials have attracted extensive interest due to their excellent electrical, thermal,mechanical, and optical properties. Graphene has been one of the most explored 2D materials. However, its zero band gap has limited its applications in electronic devices. Transition metal dichalcogenide(TMDC), another kind of 2D material,has a nonzero direct band gap(same charge carrier momentum in valence and conduction band) at monolayer state,promising for the efficient switching devices(e.g., field-effect transistors). This review mainly focuses on the recent advances in charge carrier mobility and the challenges to achieve high mobility in the electronic devices based on 2DTMDC materials and also includes an introduction of 2D materials along with the synthesis techniques. Finally, this review describes the possible methodology and future prospective to enhance the charge carrier mobility for electronic devices.
基金supported by the National Basic Research Program of China (Grant No. 2013CBA01600)the National Natural Science Foundation of China (Grant Nos. 61261160499 and 11274154)+2 种基金the National Science and Technology Major Project of the Ministry of Science and Technology of China (Grant No. 2011ZX02707)the Natural Science Foundation of Jiangsu Province, China (Grant No. BK2012302)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120091110028)
文摘Field-effect transistors （FETs） for logic applications, graphene and MoS2, are discussed. These materials have based on two representative two-dimensional （2D） materials, drastically different properties and require different consider- ations. The unique band structure of graphene necessitates engineering of the Dirac point, including the opening of the bandgap, the doping and the interface, before the graphene can be used in logic applications. On the other hand, MoS2 is a semiconductor, and its electron transport depends heavily on the surface properties, the number of layers, and the carrier density. Finally, we discuss the prospects for the future developments in 2D material transistors.
基金support by National High Technology Research and Development Program of China (No. 2011AA050504)the analysis supports from Instrumental Analysis Center of SJTU
文摘A vertical carbon nanotube field-effect transistor(CNTFET) based on silicon(Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube(SWNT) and an n-type Si nanowire in series construct the channel of the transistor. The CNTFET presents ambipolar characteristics at positive drain voltage(Vd) and n-type characteristics at negative Vd. The current is significantly influenced by the doping level of n-Si and the SWNT band gap. The n-branch current of the ambipolar characteristics increases with increasing doping level of the n-Si while the p-branch current decreases. The SWNT band gap has the same influence on the p-branch current at a positive Vd and n-type characteristics at negative Vd. The lower the SWNT band gap, the higher the current. However, it has no impact on the n-branch current in the ambipolar characteristics. Thick oxide is found to significantly degrade the current and the subthreshold slope of the CNTFETs.
基金Project supported by the National Basic Research Program of China(Grant No.2011CBA00602)the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011ZX02708-002)
文摘Various biaxial compressive strained GaSb p-channel metal-oxide-semiconductor field-effect transistors （MOSFETs） are experimentally and theoretically investigated, The biaxial compressive strained GaSb MOSFETs show a high peak mobility of 638 cm2/V.s, which is 3.86 times of the extracted mobility of the fabricated GaSb MOSFETs without strain. Meanwhile, first principles calculations show that the hole effective mass of GaSb depends on the biaxial compressive strain. The biaxiai compressive strain brings a remarkable enhancement of the hole mobility caused by a significant reduction in the hole effective mass due to the modulation of the valence bands.
基金Project supported by the Opening Project of Key Laboratory of Microelectronics Devices and Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences,the National Natural Science Foundation of China(Grant No.61574166)the National Basic Research Program of China(Grant No.2013CBA01604)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFA0201802)and the Beijing Training Project for the Leading Talents in S&T,China(Grant No.Z151100000315008)
文摘Graphene has attracted enormous interests due to its unique physical, mechanical, and electrical properties. Specially, graphene-based field-effect transistors （FETs） have evolved rapidly and are now considered as an option for conventional silicon devices. As a critical step in the design cycle of modem IC products, compact model refers to the development of models for integrated semiconductor devices for use in circuit simulations. The purpose of this review is to provide a theoretical description of current compact model of graphene field-effect transistors. Special attention is devoted to the charge sheet model, drift-diffusion model, Boltzmann equation, density of states （DOS）, and surface-potential-based compact model. Finally, an outlook of this field is briefly discussed.
基金supported by the National High Technology Research and Development Program of China(Grant No.2011AA050401)the National Science Fundfor Distinguished Young Scholars,China(Grant No.51225701)
文摘We present the design consideration and fabrication of 4H-SiC trenched-and-implanted vertical junction field-effect transistors （TI-VJFETs）. Different design factors, including channel width, channel doping, and mesa height, are con- sidered and evaluated by numerical simulations. Based on the simulation result, normally-on and normally-off devices are fabricated. The fabricated device has a 12 μm thick drift layer with 8 × 10^15 cm^-3 N-type doping and 2.6 μm channel length. The normally-on device shows a 1.2 kV blocking capability with a minimum on-state resistance of 2.33 mΩ.cm2, while the normally-off device shows an on-state resistance of 3.85 mΩ.cm2. Both the on-state and the blocking performances of the device are close to the state-of-the-art values in this voltage range.
基金Project supported by the International Science and Technology Collaboration Program of China(Grant No.2012DFG52260)
文摘In this paper, TiN/A1Ox gated A1GaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors （MOS- HFETs） were fabricated for gate-first process evaluation. By employing a low temperature ohmic process, ohmic contact can be obtained by annealing at 600 ℃ with the contact resistance approximately 1.6 Ω.mm. The ohmic annealing process also acts as a post-deposition annealing on the oxide film, resulting in good device performance. Those results demonstrated that the TiN/A1Ox gated MOS-HFETs with low temperature ohmic process can be applied for self-aligned gate AIGaN/GaN MOS-HFETs.
基金Project supported by the National Basic Research Program of China (Grant Nos. 2011CB808404 and 2009CB939703)the National Natural Science Foundation of China (Grant Nos. 10974074,90607022,60676001,60676008,and 60825403)
文摘This paper proposes an effective method of fabricating top contact organic field effect transistors by using a pho- tolithographic process. The semiconductor layer is protected by a passivation layer. Through photolithographic and etching processes, parts of the passivation layer are etched off to form source/drain electrode patterns. Combined with conventional evaporation and lift-off techniques, organic field effect transistors with a top contact are fabricated suc- cessfully, whose properties are comparable to those prepared with the shadow mask method and one order of magnitude higher than the bottom contact devices fabricated by using a photolithographic process.
基金supported by the National Natural Science Foundation of China(Grant Nos.51177175 and 61274039)the National Basic Research Project of China(Grant Nos.2010CB923200 and 2011CB301903)+4 种基金the Ph.D.Program Foundation of Ministry of Education of China(Grant No.20110171110021)the International Sci.&Tech.Collaboration Program of China(Grant No.2012DFG52260)the National High-tech R&D Program of China(Grant No.2014AA032606)the Science and Technology Plan of Guangdong Province,China(Grant No.2013B010401013)the Opened Fund of the State Key Laboratory on Integrated Optoelectronics(Grant No.IOSKL2014KF17)
文摘We report a novel structure of A1GaN/GaN heterostructure field effect transistors （HFETs） with a Si and Mg pair- doped interlayer grown on Si substrate. By optimizing the doping concentrations of the pair-doped interlayers, the mobility of 2DEG increases by twice for the conventional structure under 5 K due to the improved crystalline quality of the conduction channel. The proposed HFET shows a four orders lower off-state leakage current, resulting in a much higher on/off ratio （ - 10^9）. Further temperature-dependent performance of Schottky diodes revealed that the inhibition of shallow surface traps in proposed HFETs should be the main reason for the suppression of leakage current.
基金supported by the National Natural Science Foundation of China(Grant Nos.11174182 and 61306113)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20110131110005)
文摘A simple and effective approach to improve the switching characteristics of AlGaN/AlN/GaN heterostructure field effect transistors （HFETs） by applying a voltage bias on the substrate is presented. With the increase of the substrate bias, the OFF-state drain current is much reduced and the ON-state current keeps constant. Both the ON/OFF current ratio and the subthreshold swing are demonstrated to be greatly improved. With the thinned substrate, the improvement of the switching characteristics with the substrate bias is found to be even greater. The above improvements of the switching characteristics are attributed to the interaction between the substrate bias induced electrical field and the bulk traps in the GaN buffer layer, which reduces the conductivity of the GaN buffer layer.
基金supported by the National Natural Science Foundation of China(Grant Nos.61274096,61204043,61306042,61306045,and 61306132)the Guangdong Natural Science Foundation,China(Grant Nos.S2012010010533 and S2013040016878)+2 种基金the Shenzhen Science&Technology Foundation,China(Grant No.ZDSY20120618161735041)the Fundamental Research Project of the Shenzhen Science&Technology Foundation,China(Grant Nos.JCYJ20120618162600041,JCYJ20120618162526384,JCYJ20130402164725025,and JCYJ20120618162946025)the International Collaboration Project of the Shenzhen Science&Technology Foundation,China(Grant Nos.GJHZ20120618162120759,GJHZ20130417170946221,GJHZ20130417170908049,and GJHZ20120615142829482)
文摘An analytical model of gate-all-around （GAA） silicon nanowire tunneling field effect transistors （NW-TFETs） is developted based on the surface potential solutions in the channel direction and considering the band to band tunneling （BTBT） efficiency. The three-dimensional Poisson equation is solved to obtain the surface potential distributions in the partition regions along the channel direction for the NW-TFET, and a tunneling current model using Kane＇s expression is developed. The validity of the developed model is shown by the good agreement between the model predictions and the TCAD simulation results.
基金Project supported by the National Natural Science Foundation of China(Grant No.31872901)the National Key Research and Development Program of China(Grant No.2016YFA0501602).
文摘The luminescence intensity regulation of organic light-emitting transistor(OLED)device can be achieved effectively by the combination of graphene vertical field effect transistor(GVFET)and OLED.In this paper,we fabricate and characterize the graphene vertical field-effect transistor with gate dielectric of ion-gel film,confirming that its current switching ratio reaches up to 102.Because of the property of high light transmittance in ion-gel film,the OLED device prepared with graphene/PEDOT:PSS as composite anode exhibits good optical properties.We also prepare the graphene vertical organic light-emitting field effect transistor(GVOLEFET)by the combination of GVFET and graphene OLED,analyzing its electrical and optical properties,and confirming that the luminescence intensity can be significantly changed by regulating the gate voltage.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62004119 and 62201332)the Applied Basic Research Plan of Shanxi Province, China (Grant Nos. 20210302124647 and 20210302124028)。
文摘Nanowires with gate-all-around(GAA) structures are widely considered as the most promising candidate for 3-nm technology with the best ability of suppressing the short channel effects,and tunneling field effect transistors(TFETs)based on GAA structures also present improved performance.In this paper,a non-quasi-static(NQS) device model is developed for nanowire GAA TFETs.The model can predict the transient current and capacitance varying with operation frequency,which is beyond the ability of the quasi-static(QS) model published before.Excellent agreements between the model results and numerical simulations are obtained.Moreover,the NQS model is derived from the published QS model including the current-voltage(I-V) and capacitance-voltage(C-V) characteristics.Therefore,the NQS model is compatible with the QS model for giving comprehensive understanding of GAA TFETs and would be helpful for further study of TFET circuits based on nanowire GAA structure.
基金supported by the Fundamental Research Funds in Xidian Universities (Grant No.JY10000904009)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No.2007BAK25B03)
文摘Negative Bias Temperature Instability （NBTI） has become one of the most serious reliability problems of metaloxide-semiconductor field-effect transistors （MOSFETs）. The degradation mechanism and model of NBTI are studied in this paper. From the experimental results, the exponential value 0.25-0.5 which represents the relation of NBTI degradation and stress time is obtained. Based on the experimental results and existing model, the reaction-diffusion model with H^＋ related species generated is deduced, and the exponent 0.5 is obtained. The results suggest that there should be H^＋ generated in the NBTI degradation. With the real time method, the degradation with an exponent 0.5 appears clearly in drain current shift during the first seconds of stress and then verifies that H^＋ generated during NBTI stress.
基金Supported by the Knowledge Innovation Project of the Chinese Academy of Sciencesthe National Natural Science Foundation of China under Grant Nos 61204017 and 61334002+1 种基金the National Basic Research Program of Chinathe National Science and Technology Major Project of China
文摘Direct-current transfer characteristics of （InGaN）/A1GaN/A1N/GaN heterojunction field effect transistors （HFETs） are presented. A drain current plateau （IDs = 32.0 mA/mm） for Vcs swept from ＋0.7 V to -0. 6 V is present in the transfer characteristics of InGaN/AIGaN/AIN/GaN HFETs. The theoretical calculation shows the coexistence of two-dimensional electron gas （2DEG） and two-dimensional hole gas （2DHG） in InGaN/AIGaN/A1N/GaN heterostructures, and the screening effect of 2DHG to the 2DEG in the conduction channel can explain this current plateau. Moreover, the current plateau shows the time-dependent behavior when IDs Vcs scans repeated are conducted. The obtained insight provides indication for the design in the fabrication of GaN-based super HFETs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11604019,61574020,and 61376018)the Ministry of Science and Technology of China(Grant No.2016YFA0301300)+1 种基金the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.2016RCGD22)
文摘Tunneling field effect transistors（TFETs） based on two-dimensional materials are promising contenders to the traditional metal oxide semiconductor field effect transistor, mainly due to potential applications in low power devices. Here,we investigate the TFETs based on two different integration types： in-plane and vertical heterostructures composed of two kinds of layered phosphorous（β-P and δ-P） by ab initio quantum transport simulations. NDR effects have been observed in both in-plane and vertical heterostructures, and the effects become significant with the highest peak-to-valley ratio（PVR）when the intrinsic region length is near zero. Compared with the in-plane TFET based on β-P and δ-P, better performance with a higher on/off current ratio of - 10-6 and a steeper subthreshold swing（SS） of - 23 mV/dec is achieved in the vertical TFET. Such differences in the NDR effects, on/off current ratio and SS are attributed to the distinct interaction nature of theβ-P and δ-P layers in the in-plane and vertical heterostructures.
