Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electro...Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electron gas(2DEG)channel.The fabricated E-mode HEMTs exhibit a relatively high threshold voltage(VTH)of+1.1 V with good uniformity.A maxi-mum current/power gain cut-off frequency(fT/fMAX)of 31.3/99.6 GHz with a power added efficiency(PAE)of 52.47%and an out-put power density(Pout)of 1.0 W/mm at 3.5 GHz were achieved on the fabricated E-mode HEMTs with 1-μm gate and Au-free ohmic contact.展开更多
An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors(HEMTs)is proposed,which considers a dual-field-plate(FP)made up of a gate-FP and a source-FP.The equivalent circui...An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors(HEMTs)is proposed,which considers a dual-field-plate(FP)made up of a gate-FP and a source-FP.The equivalent circuit of the overall model is composed of parasitic elements,intrinsic transistors,gate-FP,and source-FP networks.The equivalent circuit of the gate-FP is identical to that of the intrinsic transistor.In order to simplify the complexity of the model,a series combination of a resistor and a capacitor is employed to represent the source-FP.The analytical extraction procedure of the model parameters is presented based on the proposed equivalent circuit.The verification is carried out on a 4×250μm GaN HEMT device with a gate-FP and a source-FP in a 0.45μm technology.Compared with the classic model,the proposed novel small-signal model shows closer agreement with measured S-parameters in the range of 1.0 to 18.0 GHz.展开更多
The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is obser...The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is observed that the threshold voltage shows a significant negative shift during the typical long-term on-state gate overdrive stress. The degradation does not originate from the presence of as-grown traps in the Al Ga N barrier layer or the generated traps during fluorine ion implantation process. By comparing the relationships between the shift of threshold voltage and the cumulative injected electrons under different stress conditions, a good agreement is observed. It provides direct experimental evidence to support the impact ionization physical model, in which the degradation of E-mode HEMTs under gate overdrive stress can be explained by the ionization of fluorine ions in the Al Ga N barrier layer by electrons injected from 2DEG channel.Furthermore, our results show that there are few new traps generated in the Al Ga N barrier layer during the gate overdrive stress, and the ionized fluorine ions cannot recapture the electrons.展开更多
Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×10^(12)cm^(-2), together with a high ele...Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×10^(12)cm^(-2), together with a high electron mobility of1229.5 cm^2/V·s, was obtained for the prepared heterostructures. The surface morphology of the heterostructures was also significantly improved, i.e., with a root mean square roughness of 0.29 nm in a 2 μm×2 μm scan area. In addition to the improved properties, the enhancement-mode metal–oxide–semiconductor high electron mobility transistors(MOSHEMTs) processed on the heterostructures not only exhibited a high threshold voltage(VTH) of 3.1 V, but also demonstrated a significantly enhanced drain output current density of 669 m A/mm. These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge. This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.展开更多
Wide-bandgap devices,such as silicon-carbide metal-oxide-semiconductor field-effect transistors(MOSFETs)and gallium-nitride high electron mobility transistors(HEMTs),exhibit an excellent figure of merits compared to c...Wide-bandgap devices,such as silicon-carbide metal-oxide-semiconductor field-effect transistors(MOSFETs)and gallium-nitride high electron mobility transistors(HEMTs),exhibit an excellent figure of merits compared to conventional silicon devices.Challenges of applying such fast switches include accurate extraction and optimization of parasitics especially when 6high-efficiency operation,all of which require the comprehensive understanding of such switch especially its interaction with peripheral circuits.Particularly for the enhancement-mode GaN HEMTs without the intrinsic body diode,when reverse conducting,its high voltage drop causes a high dead-time loss,which has rarely a concern in silicon devices.This paper focuses on 650V/30~60A enhancement-mode GaN HEMTs provided by GaN Systems,analytically models its switching behaviors,summarizes the impact of parasitics and dead time,and applies it in two DC/DC converters.Systematic design rules are generated not only for soft switching but also for hard switching applications.展开更多
When using traditional drive circuits,the enhancement-mode GaN(eGaN)HEMT will be affected by high switching speed characteristics and parasitic parameters leading to worse crosstalk problems.Currently,the existing cro...When using traditional drive circuits,the enhancement-mode GaN(eGaN)HEMT will be affected by high switching speed characteristics and parasitic parameters leading to worse crosstalk problems.Currently,the existing crosstalk suppression drive circuits often have the disadvantages of increased switching loss,control complexity,and overall electromagnetic interference(EMI).Therefore,this paper combines the driving loop impedance control and the active Miller clamp method to propose an improved active Miller clamp drive circuit.First,the crosstalk mechanism is analyzed,and the crosstalk voltage model is established.Through the crosstalk voltage evaluation platform,the influencing factors are evaluated experimentally.Then,the operating principle of the improved active Miller clamp drive circuit is discussed,and the optimized parameter design method is given.Finally,the effect of the improved active Miller clamp method for suppressing crosstalk is experimentally verified.The crosstalk voltage was suppressed from 3.5 V and-3.5 V to 1 V and-1.3 V,respectively,by the improved circuit.展开更多
An extraction method of the component parameter values of an enhancement-mode InGaP/AIGaAs/In-GaAs PHEMT small signal equivalent circuit is presented,and these component parameter values are extracted by using the EEH...An extraction method of the component parameter values of an enhancement-mode InGaP/AIGaAs/In-GaAs PHEMT small signal equivalent circuit is presented,and these component parameter values are extracted by using the EEHEMT1 model of IC-CAP software. The extraction results are verified by ADS software,and the DC I-V curves and S parameters simulated by ADS are basically accordant with those of the test results. These results indicate that the EEHEMT1 model can be used for extracting the component parameters of an enhancement-mode PHEMT.展开更多
For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- taine...For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- tained. Using the structure of Ti/Pt/Au, about a 200mV positive shift of threshold voltage is achieved by thermal annea- ling at 320℃ for 40min in N2 ambient. Finally, a stable and consistent enhancement-mode PHEMT is produced successfully with higher threshold voltage.展开更多
In this work,the GaN p-MISFET with LPCVD-SiN_(x) is studied as a gate dielectric to improve device performance.By changing the Si/N stoichiometry of SiN_(x),it is found that the channel hole mobility can be effectivel...In this work,the GaN p-MISFET with LPCVD-SiN_(x) is studied as a gate dielectric to improve device performance.By changing the Si/N stoichiometry of SiN_(x),it is found that the channel hole mobility can be effectively enhanced with Si-rich SiN_(x) gate dielectric,which leads to a respectably improved drive current of GaN p-FET.The record high channel mobility of 19.4 cm2/(V∙s)was achieved in the device featuring an Enhancement-mode channel.Benefiting from the significantly improved channel mobility,the fabricated E-mode GaN p-MISFET is capable of delivering a decent-high current of 1.6 mA/mm,while simultaneously featuring a negative threshold-voltage(VTH)of–2.3 V(defining at a stringent criteria of 10μA/mm).The device also exhibits a well pinch-off at 0 V with low leakage current of 1 nA/mm.This suggests that a decent E-mode operation of the fabricated p-FET is obtained.In addition,the VTH shows excellent stability,while the threshold-voltage hysteresisΔVTH is as small as 0.1 V for a gate voltage swing up to–10 V,which is among the best results reported in the literature.The results indicate that optimizing the Si/N stoichiometry of LPCVD-SiN_(x) is a promising approach to improve the device performance of GaN p-MISFET.展开更多
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFB3604400in part by the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)+4 种基金in part by CAS-Croucher Funding Scheme under Grant CAS22801in part by National Natural Science Foundation of China under Grant 62074161,Grant 62004213,and Grant U20A20208in part by the Beijing Municipal Science and Technology Commission project under Grant Z201100008420009 and Grant Z211100007921018in part by the University of CASin part by IMECAS-HKUST-Joint Laboratory of Microelectronics.
文摘Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electron gas(2DEG)channel.The fabricated E-mode HEMTs exhibit a relatively high threshold voltage(VTH)of+1.1 V with good uniformity.A maxi-mum current/power gain cut-off frequency(fT/fMAX)of 31.3/99.6 GHz with a power added efficiency(PAE)of 52.47%and an out-put power density(Pout)of 1.0 W/mm at 3.5 GHz were achieved on the fabricated E-mode HEMTs with 1-μm gate and Au-free ohmic contact.
基金the National Natural Science Foundation of China(62304252)the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)and IMECAS-HKUST-Joint Laboratory of Microelectronics。
文摘An accurate and novel small-signal equivalent circuit model for GaN high-electron-mobility transistors(HEMTs)is proposed,which considers a dual-field-plate(FP)made up of a gate-FP and a source-FP.The equivalent circuit of the overall model is composed of parasitic elements,intrinsic transistors,gate-FP,and source-FP networks.The equivalent circuit of the gate-FP is identical to that of the intrinsic transistor.In order to simplify the complexity of the model,a series combination of a resistor and a capacitor is employed to represent the source-FP.The analytical extraction procedure of the model parameters is presented based on the proposed equivalent circuit.The verification is carried out on a 4×250μm GaN HEMT device with a gate-FP and a source-FP in a 0.45μm technology.Compared with the classic model,the proposed novel small-signal model shows closer agreement with measured S-parameters in the range of 1.0 to 18.0 GHz.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61334002,61106106,and 61474091)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(Grant No.ZHD201206)+1 种基金the New Experiment Development Funds for Xidian University,China(Grant No.SY1213)the Scientific Research Foundation for the Returned Overseas Chinese Scholars
文摘The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is observed that the threshold voltage shows a significant negative shift during the typical long-term on-state gate overdrive stress. The degradation does not originate from the presence of as-grown traps in the Al Ga N barrier layer or the generated traps during fluorine ion implantation process. By comparing the relationships between the shift of threshold voltage and the cumulative injected electrons under different stress conditions, a good agreement is observed. It provides direct experimental evidence to support the impact ionization physical model, in which the degradation of E-mode HEMTs under gate overdrive stress can be explained by the ionization of fluorine ions in the Al Ga N barrier layer by electrons injected from 2DEG channel.Furthermore, our results show that there are few new traps generated in the Al Ga N barrier layer during the gate overdrive stress, and the ionized fluorine ions cannot recapture the electrons.
基金Project supported by the National Postdoctoral Program for Innovative Talents,China(Grant No.BX201700184)the National Key Research and Development Program of China(Grant Nos.2016YFB0400105 and 2017YFB0403102)
文摘Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×10^(12)cm^(-2), together with a high electron mobility of1229.5 cm^2/V·s, was obtained for the prepared heterostructures. The surface morphology of the heterostructures was also significantly improved, i.e., with a root mean square roughness of 0.29 nm in a 2 μm×2 μm scan area. In addition to the improved properties, the enhancement-mode metal–oxide–semiconductor high electron mobility transistors(MOSHEMTs) processed on the heterostructures not only exhibited a high threshold voltage(VTH) of 3.1 V, but also demonstrated a significantly enhanced drain output current density of 669 m A/mm. These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge. This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.
文摘Wide-bandgap devices,such as silicon-carbide metal-oxide-semiconductor field-effect transistors(MOSFETs)and gallium-nitride high electron mobility transistors(HEMTs),exhibit an excellent figure of merits compared to conventional silicon devices.Challenges of applying such fast switches include accurate extraction and optimization of parasitics especially when 6high-efficiency operation,all of which require the comprehensive understanding of such switch especially its interaction with peripheral circuits.Particularly for the enhancement-mode GaN HEMTs without the intrinsic body diode,when reverse conducting,its high voltage drop causes a high dead-time loss,which has rarely a concern in silicon devices.This paper focuses on 650V/30~60A enhancement-mode GaN HEMTs provided by GaN Systems,analytically models its switching behaviors,summarizes the impact of parasitics and dead time,and applies it in two DC/DC converters.Systematic design rules are generated not only for soft switching but also for hard switching applications.
基金supported by the Foundation of State Key Laboratory of Wide-Bandgap Semi-conductor Power Electronic Devices(No.2019KF001)National Natural Science Foundation of China(No.51677089)。
文摘When using traditional drive circuits,the enhancement-mode GaN(eGaN)HEMT will be affected by high switching speed characteristics and parasitic parameters leading to worse crosstalk problems.Currently,the existing crosstalk suppression drive circuits often have the disadvantages of increased switching loss,control complexity,and overall electromagnetic interference(EMI).Therefore,this paper combines the driving loop impedance control and the active Miller clamp method to propose an improved active Miller clamp drive circuit.First,the crosstalk mechanism is analyzed,and the crosstalk voltage model is established.Through the crosstalk voltage evaluation platform,the influencing factors are evaluated experimentally.Then,the operating principle of the improved active Miller clamp drive circuit is discussed,and the optimized parameter design method is given.Finally,the effect of the improved active Miller clamp method for suppressing crosstalk is experimentally verified.The crosstalk voltage was suppressed from 3.5 V and-3.5 V to 1 V and-1.3 V,respectively,by the improved circuit.
文摘An extraction method of the component parameter values of an enhancement-mode InGaP/AIGaAs/In-GaAs PHEMT small signal equivalent circuit is presented,and these component parameter values are extracted by using the EEHEMT1 model of IC-CAP software. The extraction results are verified by ADS software,and the DC I-V curves and S parameters simulated by ADS are basically accordant with those of the test results. These results indicate that the EEHEMT1 model can be used for extracting the component parameters of an enhancement-mode PHEMT.
文摘For enhancement-mode InGaP/A1GaAs/InGaAs PHEMTs,gate annealing is conducted between gate structures of Ti/Pt/Au and Pt/Ti/Pt/Au. Comparison is made after thermal annealing and an optimum annealing process is ob- tained. Using the structure of Ti/Pt/Au, about a 200mV positive shift of threshold voltage is achieved by thermal annea- ling at 320℃ for 40min in N2 ambient. Finally, a stable and consistent enhancement-mode PHEMT is produced successfully with higher threshold voltage.
基金This work was supported in part by the Natural Science Foundation of China under Grant 62174019in part by the Guangdong Basic and Applied Basic Research Foundation China under Grant 2021B1515140039in part by the Zhuhai Industry-University Research Cooperation Project under Grant ZH22017001210041PWC.
文摘In this work,the GaN p-MISFET with LPCVD-SiN_(x) is studied as a gate dielectric to improve device performance.By changing the Si/N stoichiometry of SiN_(x),it is found that the channel hole mobility can be effectively enhanced with Si-rich SiN_(x) gate dielectric,which leads to a respectably improved drive current of GaN p-FET.The record high channel mobility of 19.4 cm2/(V∙s)was achieved in the device featuring an Enhancement-mode channel.Benefiting from the significantly improved channel mobility,the fabricated E-mode GaN p-MISFET is capable of delivering a decent-high current of 1.6 mA/mm,while simultaneously featuring a negative threshold-voltage(VTH)of–2.3 V(defining at a stringent criteria of 10μA/mm).The device also exhibits a well pinch-off at 0 V with low leakage current of 1 nA/mm.This suggests that a decent E-mode operation of the fabricated p-FET is obtained.In addition,the VTH shows excellent stability,while the threshold-voltage hysteresisΔVTH is as small as 0.1 V for a gate voltage swing up to–10 V,which is among the best results reported in the literature.The results indicate that optimizing the Si/N stoichiometry of LPCVD-SiN_(x) is a promising approach to improve the device performance of GaN p-MISFET.
