With the analysis of experiment and theory on GaN HEMT devices under DC sweep,an improved model for kink effect based on advanced SPICE model for high electron mobility transistors(ASM-HEMT)is pro⁃posed,considering th...With the analysis of experiment and theory on GaN HEMT devices under DC sweep,an improved model for kink effect based on advanced SPICE model for high electron mobility transistors(ASM-HEMT)is pro⁃posed,considering the relationship between the drain/gate-source voltage and kink effect.The improved model can not only accurately describe the trend of the drain-source current with the current collapse and kink effect,but also precisely fit different values of drain-source voltages at which the kink effect occurs under different gatesource voltages.Furthermore,it well characterizes the DC characteristics of GaN devices in the full operating range,with the fitting error less than 3%.To further verify the accuracy and convergence of the improved model,a load-pull system is built in ADS.The simulated result shows that although both the original ASM-HEMT and the improved model predict the output power for the maximum power matching of GaN devices well,the im⁃proved model predicts the power-added efficiency for the maximum efficiency matching more accurately,with 4%improved.展开更多
In this paper, a new current expression based on both the direct currect （DC） characteristics of the A1GaN/GaN high election mobility transistor （HEMT） and the hyperbolic tangent function tanh is proposed, by whic...In this paper, a new current expression based on both the direct currect （DC） characteristics of the A1GaN/GaN high election mobility transistor （HEMT） and the hyperbolic tangent function tanh is proposed, by which we can describe the kink effect of the A1GaN/GaN HEMT well. Then, an improved EEHEMT model including the proposed current expression is presented. The simulated and measured results of Ⅰ-Ⅴ, S-parameter, and radio frequency （RF） large-signal characteristics are compared for a self-developed on-wafer A1GaN/GaN HEMT with ten gate fingers each being 0.4-μm long and 125-p-m wide （Such an A1GaN/GaN HEMT is denoted as A1GaN/GaN HEMT （10 × 125 μm））. The improved large signal model simulates the Ⅰ-Ⅴ characteristic much more accurately than the original one, and its transconductance and RF characteristics are also in excellent agreement with the measured data.展开更多
The kink effect in current-voltage （IV） characteristic s seriously deteriorates the performance of a GaN-based HEMT. Based on a series of direct current （DC） IV measurements in a GaN-based HEMT with an AlGaN back ...The kink effect in current-voltage （IV） characteristic s seriously deteriorates the performance of a GaN-based HEMT. Based on a series of direct current （DC） IV measurements in a GaN-based HEMT with an AlGaN back barrier, a possible mechanism with electron-trapping and detrapping processes is proposed. Kink-related deep levels are activated by a high drain source voltage （Vds） and located in a GaN channel layer. Both electron trapping and detrapping processes are accomplished with the help of hot electrons from the channel by impact ionization. Moreover, the mechanism is verified by two other DC IV measurements and a model with an expression of the kink current.展开更多
The kink effect is studied in an AlGaN/GaN high electron mobility transistor by measuring DC performance during fresh, short-term stress and recovery cycle with negligible degradation. Vdg plays an assistant role in d...The kink effect is studied in an AlGaN/GaN high electron mobility transistor by measuring DC performance during fresh, short-term stress and recovery cycle with negligible degradation. Vdg plays an assistant role in detrapping electrons and short-term stress results in no creation of new category traps but an increase in number of active traps. A possible mechanism is proposed that electrical stress supplies traps with the electric field for activation and when device is under test field-assisted hot-electrons result in electrons detrapping from traps, thus deteriorating the kink effect. In addition, experiments show that the impact ionization is at a relatively low level, which is not the dominant mechanism compared with trapping effect. We analyse the complicated link between the kink effect and stress bias through groups of electrical stress states： Pals = 0-state, off-state, on-state （on-state with low voltage, high-power state, high field state）. Finlly, a conclusion is drawn that electric field brings about more severe kink effect than hot electrons. With the assistance of electric field, hot electrons tend to be possible to modulate the charges in deep-level trap.展开更多
Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach t...Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach that is easily incorporated into most existing empirical HEMT I-V models. This has been done by modifying the channel length modulation parameter to account for the kink effect. Moreover, the definitions of the left parameters in the original model will not be influenced, and the improved HEMT I-V model enhances its bias range of operation for which accuracy is maintained. The proposed modeling method is validated through DC/ Pulsed I-V as well as large-signal power measurements.展开更多
Several methods of characterization of trap levels like I-V, C-V and transient spectroscopy (DLTS) were used to determine the accurate values of the activation energies of traps present in N+P junctions obtained after...Several methods of characterization of trap levels like I-V, C-V and transient spectroscopy (DLTS) were used to determine the accurate values of the activation energies of traps present in N+P junctions obtained after retrograde profile implantation of indium and boron on silicon. Four main traps located at Ev + 0.15 eV, Ev + 0.21 eV, Ev + 0.28 eV and Ev + 0.46 eV are reported. Shallow levels are also calculated from I-V characteristics. Concurrently, indium channel doped NMOSFETs are investigated showing the kink phenomenon. In order to discuss the relationship between the kink effect and the active indium trap level situated at 0.16 eV, the transient effects are studied by varying the integration time and the temperature. The effects of substrate polarization are also carried out showing the reduction of the kink with the bulk positive polarization.展开更多
多晶硅薄膜晶体管(P-Si TFTs)技术在SOP(system on panel)显示应用中发挥着越来越重要的作用。随着尺寸的不断缩小,P-Si TFT的Kink效应越来越明显,对有源液晶显示矩阵和驱动电路的性能影响很大。对发生Kink效应的物理机制、二维数值仿...多晶硅薄膜晶体管(P-Si TFTs)技术在SOP(system on panel)显示应用中发挥着越来越重要的作用。随着尺寸的不断缩小,P-Si TFT的Kink效应越来越明显,对有源液晶显示矩阵和驱动电路的性能影响很大。对发生Kink效应的物理机制、二维数值仿真及其一维解析模型进行了分析,讨论了晶粒边界、沟道长度与Kink效应的关系,提出建立适合电路仿真的一维解析模型的关键与展望。展开更多
The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependent internal friction was studied.The longitudinal bias stress may always weaken the anomalous amplitude-dependent effect,while th...The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependent internal friction was studied.The longitudinal bias stress may always weaken the anomalous amplitude-dependent effect,while the torsional one may induce different effects from differ- ent directions applied.Bias stress effect exhibits only in properly heat treated and cold worked ahoy specimens.The anomalous amplitude-dependent internal friction peaks,P_3,P_2 and P_1, are found to be related closely to slant dislocation kink chains.Thus,the application of bias stress to internal friction would be contributed to the study on dislocation structure.展开更多
FB （floating-body） and BC （body-contact） partially depleted SOI nMOSFETs with HBC（half-back-channel） implantation are fabricated. Test results show that such devices have good performance in delaying the occurre...FB （floating-body） and BC （body-contact） partially depleted SOI nMOSFETs with HBC（half-back-channel） implantation are fabricated. Test results show that such devices have good performance in delaying the occurrence of the “kink” phenomenon and improving the breakdown voltage as compared to conventional PDSOI nMOS- FETs,while not decreasing the threshold voltage of the back gate obviously. Numerical simulation shows that a reduced electrical field in the drain contributes to the improvement of the breakdown voltage and a delay of the “kink” effect. A detailed analysis is given for the cause of such improvement of breakdown voltage and the delay of the “kink” effect.展开更多
A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of ...A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.展开更多
基金Supported by the National Key R&D Program of China(2022YFF0707800,2022YFF0707801)Primary Research&Development Plan of Jiangsu Province(BE2022070,BE2022070-2)。
文摘With the analysis of experiment and theory on GaN HEMT devices under DC sweep,an improved model for kink effect based on advanced SPICE model for high electron mobility transistors(ASM-HEMT)is pro⁃posed,considering the relationship between the drain/gate-source voltage and kink effect.The improved model can not only accurately describe the trend of the drain-source current with the current collapse and kink effect,but also precisely fit different values of drain-source voltages at which the kink effect occurs under different gatesource voltages.Furthermore,it well characterizes the DC characteristics of GaN devices in the full operating range,with the fitting error less than 3%.To further verify the accuracy and convergence of the improved model,a load-pull system is built in ADS.The simulated result shows that although both the original ASM-HEMT and the improved model predict the output power for the maximum power matching of GaN devices well,the im⁃proved model predicts the power-added efficiency for the maximum efficiency matching more accurately,with 4%improved.
基金Project supported by the National Natural Science Foundation of China(Grant No.61334002)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(Grant No.ZHD201206)the Program for New Century Excellent Talents in University(Grant No.NCET-12-0915)
文摘In this paper, a new current expression based on both the direct currect （DC） characteristics of the A1GaN/GaN high election mobility transistor （HEMT） and the hyperbolic tangent function tanh is proposed, by which we can describe the kink effect of the A1GaN/GaN HEMT well. Then, an improved EEHEMT model including the proposed current expression is presented. The simulated and measured results of Ⅰ-Ⅴ, S-parameter, and radio frequency （RF） large-signal characteristics are compared for a self-developed on-wafer A1GaN/GaN HEMT with ten gate fingers each being 0.4-μm long and 125-p-m wide （Such an A1GaN/GaN HEMT is denoted as A1GaN/GaN HEMT （10 × 125 μm））. The improved large signal model simulates the Ⅰ-Ⅴ characteristic much more accurately than the original one, and its transconductance and RF characteristics are also in excellent agreement with the measured data.
基金Project supported by the Program for New Century Excellent Talents in University,China (Grant No.NCET-12-0915)
文摘The kink effect in current-voltage （IV） characteristic s seriously deteriorates the performance of a GaN-based HEMT. Based on a series of direct current （DC） IV measurements in a GaN-based HEMT with an AlGaN back barrier, a possible mechanism with electron-trapping and detrapping processes is proposed. Kink-related deep levels are activated by a high drain source voltage （Vds） and located in a GaN channel layer. Both electron trapping and detrapping processes are accomplished with the help of hot electrons from the channel by impact ionization. Moreover, the mechanism is verified by two other DC IV measurements and a model with an expression of the kink current.
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB309606)
文摘The kink effect is studied in an AlGaN/GaN high electron mobility transistor by measuring DC performance during fresh, short-term stress and recovery cycle with negligible degradation. Vdg plays an assistant role in detrapping electrons and short-term stress results in no creation of new category traps but an increase in number of active traps. A possible mechanism is proposed that electrical stress supplies traps with the electric field for activation and when device is under test field-assisted hot-electrons result in electrons detrapping from traps, thus deteriorating the kink effect. In addition, experiments show that the impact ionization is at a relatively low level, which is not the dominant mechanism compared with trapping effect. We analyse the complicated link between the kink effect and stress bias through groups of electrical stress states： Pals = 0-state, off-state, on-state （on-state with low voltage, high-power state, high field state）. Finlly, a conclusion is drawn that electric field brings about more severe kink effect than hot electrons. With the assistance of electric field, hot electrons tend to be possible to modulate the charges in deep-level trap.
文摘Short gate-length High Electron Mobility Transistors (HEMTs) have been observed to exhibit kinks in their drain current-voltage (I-V) characteristics. To model this nonlinear effect, we present an effective approach that is easily incorporated into most existing empirical HEMT I-V models. This has been done by modifying the channel length modulation parameter to account for the kink effect. Moreover, the definitions of the left parameters in the original model will not be influenced, and the improved HEMT I-V model enhances its bias range of operation for which accuracy is maintained. The proposed modeling method is validated through DC/ Pulsed I-V as well as large-signal power measurements.
文摘Several methods of characterization of trap levels like I-V, C-V and transient spectroscopy (DLTS) were used to determine the accurate values of the activation energies of traps present in N+P junctions obtained after retrograde profile implantation of indium and boron on silicon. Four main traps located at Ev + 0.15 eV, Ev + 0.21 eV, Ev + 0.28 eV and Ev + 0.46 eV are reported. Shallow levels are also calculated from I-V characteristics. Concurrently, indium channel doped NMOSFETs are investigated showing the kink phenomenon. In order to discuss the relationship between the kink effect and the active indium trap level situated at 0.16 eV, the transient effects are studied by varying the integration time and the temperature. The effects of substrate polarization are also carried out showing the reduction of the kink with the bulk positive polarization.
文摘多晶硅薄膜晶体管(P-Si TFTs)技术在SOP(system on panel)显示应用中发挥着越来越重要的作用。随着尺寸的不断缩小,P-Si TFT的Kink效应越来越明显,对有源液晶显示矩阵和驱动电路的性能影响很大。对发生Kink效应的物理机制、二维数值仿真及其一维解析模型进行了分析,讨论了晶粒边界、沟道长度与Kink效应的关系,提出建立适合电路仿真的一维解析模型的关键与展望。
文摘The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependent internal friction was studied.The longitudinal bias stress may always weaken the anomalous amplitude-dependent effect,while the torsional one may induce different effects from differ- ent directions applied.Bias stress effect exhibits only in properly heat treated and cold worked ahoy specimens.The anomalous amplitude-dependent internal friction peaks,P_3,P_2 and P_1, are found to be related closely to slant dislocation kink chains.Thus,the application of bias stress to internal friction would be contributed to the study on dislocation structure.
文摘FB （floating-body） and BC （body-contact） partially depleted SOI nMOSFETs with HBC（half-back-channel） implantation are fabricated. Test results show that such devices have good performance in delaying the occurrence of the “kink” phenomenon and improving the breakdown voltage as compared to conventional PDSOI nMOS- FETs,while not decreasing the threshold voltage of the back gate obviously. Numerical simulation shows that a reduced electrical field in the drain contributes to the improvement of the breakdown voltage and a delay of the “kink” effect. A detailed analysis is given for the cause of such improvement of breakdown voltage and the delay of the “kink” effect.
文摘A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.
