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
In this paper, a new current expression based on both the direct currect(DC) characteristics of the AlGaN/GaN high election mobility transistor(HEMT) and the hyperbolic tangent function tanh is proposed, by which we c...In this paper, a new current expression based on both the direct currect(DC) characteristics of the AlGaN/GaN high election mobility transistor(HEMT) and the hyperbolic tangent function tanh is proposed, by which we can describe the kink effect of the AlGaN/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 AlGaN/GaN HEMT with ten gate fingers each being 0.4-μm long and 125-μm wide(Such an AlGaN/GaN HEMT is denoted as AlGaN/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 barrier,...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: Vds = 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
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-dependentinternal friction was studied.The longitudinal bias stress may always weaken the anomalousamplitude-dependent effect,while the ...The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependentinternal friction was studied.The longitudinal bias stress may always weaken the anomalousamplitude-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 workedahoy specimens.The anomalous amplitude-dependent internal friction peaks,P<sub>3</sub>,P<sub>2</sub> and P<sub>1</sub>,are found to be related closely to slant dislocation kink chains.Thus,the application of biasstress to internal friction would be contributed to the study on dislocation structure.展开更多
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.
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 AlGaN/GaN high election mobility transistor(HEMT) and the hyperbolic tangent function tanh is proposed, by which we can describe the kink effect of the AlGaN/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 AlGaN/GaN HEMT with ten gate fingers each being 0.4-μm long and 125-μm wide(Such an AlGaN/GaN HEMT is denoted as AlGaN/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: Vds = 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-dependentinternal friction was studied.The longitudinal bias stress may always weaken the anomalousamplitude-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 workedahoy specimens.The anomalous amplitude-dependent internal friction peaks,P<sub>3</sub>,P<sub>2</sub> and P<sub>1</sub>,are found to be related closely to slant dislocation kink chains.Thus,the application of biasstress to internal friction would be contributed to the study on dislocation structure.
