Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching mea...Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching measurements.The overhang capacitances induce a pinch-off voltage distinguished from that of the E-mode channel capacitance in the gate capacitance and the gatedrain capacitance characteristic curves.Frequency-and voltage-dependent tests confirm the instability caused by the trapping of interface/bulk states in the LPCVD-SiNx passivation dielectric.Circuit-level double pulse measurement also reveals its impact on switching transition for power switching applications.展开更多
The leakage current and breakdown voltage of AlGaN/GaN/AlGaN high electron mobility transistors on silicon with different GaN channel thicknesses were investigated.The results showed that a thin GaN channel was benefi...The leakage current and breakdown voltage of AlGaN/GaN/AlGaN high electron mobility transistors on silicon with different GaN channel thicknesses were investigated.The results showed that a thin GaN channel was beneficial for obtaining a high breakdown voltage,based on the leakage current path and the acceptor traps in the AlGaN back-barrier.The breakdown voltage of the device with an 800 nm-thick GaN channel was 926 V@1 m A/mm,and the leakage current increased slowly between 300 and 800 V.Besides,the raising conduction band edge of the GaN channel by the AlGaN back-barrier lead to little degradation for sheet 2-D electron gas density,especially,in the thin GaN channel.The transfer and output characteristics were not obviously deteriorated for the samples with different GaN channel thickness.Through optimizing the GaN channel thickness and designing the Al GaN back-barrier,the lower leakage current and higher breakdown voltage would be possible.展开更多
Two types of enhancement-mode(E-mode)AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MIS-HEMTs)with different gate insulators are fabricated on Si substrates.The HfO2 gate insulator and the ...Two types of enhancement-mode(E-mode)AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MIS-HEMTs)with different gate insulators are fabricated on Si substrates.The HfO2 gate insulator and the Al2O3 gate insulator each with a thickness of 30 nm are grown by the plasma-enhanced atomic layer deposition(PEALD).The energy band diagrams of two types of dielectric MIS-HEMTs are compared.The breakdown voltage(VBR)of HfO2 dielectric layer and Al2O3 dielectric layer are 9.4 V and 15.9 V,respectively.With the same barrier thickness,the transconductance of MIS-HEMT with HfO2 is larger.The threshold voltage(Vth)of the HfO2 and Al2O3 MIS-HEMT are 2.0 V and 2.4 V,respectively,when the barrier layer thickness is 0 nm.The C-V characteristics are in good agreement with the Vth's transfer characteristics.As the barrier layer becomes thinner,the drain current density decreases sharply.Due to the dielectric/AlGaN interface is very close to the channel,the scattering of interface states will lead the electron mobility to decrease.The current collapse and the Ron of Al2O3 MIS-HEMT are smaller at the maximum gate voltage.As Al2O3 has excellent thermal stability and chemical stability,the interface state density of Al2O3/AlGaN is less than that of HfO2/AlGaN.展开更多
In this letter,high power density AlGaN/GaN high electron-mobility transistors(HEMTs)on a freestanding GaN substrate are reported.An asymmetricΓ-shaped 500-nm gate with a field plate of 650 nm is introduced to improv...In this letter,high power density AlGaN/GaN high electron-mobility transistors(HEMTs)on a freestanding GaN substrate are reported.An asymmetricΓ-shaped 500-nm gate with a field plate of 650 nm is introduced to improve microwave power performance.The breakdown voltage(BV)is increased to more than 200 V for the fabricated device with gate-to-source and gate-to-drain distances of 1.08 and 2.92μm.A record continuous-wave power density of 11.2 W/mm@10 GHz is realized with a drain bias of 70 V.The maximum oscillation frequency(f_(max))and unity current gain cut-off frequency(f_(t))of the AlGaN/GaN HEMTs exceed 30 and 20 GHz,respectively.The results demonstrate the potential of AlGaN/GaN HEMTs on freestanding GaN substrates for microwave power applications.展开更多
In this study, the effects of 1 MeV electron radiation on the D-mode GaN-based high electron mobility transistors(HEMTs) were investigated after different radiation doses. The changes in electrical properties of the d...In this study, the effects of 1 MeV electron radiation on the D-mode GaN-based high electron mobility transistors(HEMTs) were investigated after different radiation doses. The changes in electrical properties of the device were obtained, and the related physical mechanisms were analyzed. It indicated that under the radiation dose of 5 × 10^(14) cm^(-2), the channel current cannot be completely pinched off even if the negative gate voltage was lower than the threshold voltage, and the gate leakage current increased significantly. The emission microscopy and scanning electron microscopy were used to determine the damage location. Besides, the radiation dose was adjusted ranging from 5 × 10^(12) to 1 × 10^(14) cm^(-2), and we noticed that the drain-source current increased and the threshold voltage presented slightly negative shift. By calculations, it suggested that the carrier density and electron mobility gradually increased. It provided a reference for the development of device radiation reinforcement technology.展开更多
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
基金the National Natural Science Foundation of China under Grant 61822407,Grant 61527816,Grant 11634002,Grant 61631021,Grant 62074161,Grant 62004213,and Grant U20A20208in part by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)under Grant QYZDB-SSW-JSC012+2 种基金in part by the Youth Innovation Promotion Association of CASin part by the University of CASthe Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,CAS.
文摘Parasitic capacitances associated with overhangs of the T-shape-gate enhancement-mode(E-mode)GaN-based power device,were investigated by frequency/voltage-dependent capacitance-voltage and inductive-load switching measurements.The overhang capacitances induce a pinch-off voltage distinguished from that of the E-mode channel capacitance in the gate capacitance and the gatedrain capacitance characteristic curves.Frequency-and voltage-dependent tests confirm the instability caused by the trapping of interface/bulk states in the LPCVD-SiNx passivation dielectric.Circuit-level double pulse measurement also reveals its impact on switching transition for power switching applications.
基金supported by the Key Research and Development Program of Jiangsu Province(No.BE2016084)the National Natural Science Foundation of China(Nos.11404372,6157401,61704185)+3 种基金the Natural Science Foundation of Beijing,China(No.4182015)the Scientific Research Fund Project of Municipal Education Commission of Beijing(No.PXM2017_014204_500034)the National Key Scientific Instrument and Equipment Development Projects of China(No.2013YQ470767)the National Key Research and Development Program of China(No.2016YFC0801203)
文摘The leakage current and breakdown voltage of AlGaN/GaN/AlGaN high electron mobility transistors on silicon with different GaN channel thicknesses were investigated.The results showed that a thin GaN channel was beneficial for obtaining a high breakdown voltage,based on the leakage current path and the acceptor traps in the AlGaN back-barrier.The breakdown voltage of the device with an 800 nm-thick GaN channel was 926 V@1 m A/mm,and the leakage current increased slowly between 300 and 800 V.Besides,the raising conduction band edge of the GaN channel by the AlGaN back-barrier lead to little degradation for sheet 2-D electron gas density,especially,in the thin GaN channel.The transfer and output characteristics were not obviously deteriorated for the samples with different GaN channel thickness.Through optimizing the GaN channel thickness and designing the Al GaN back-barrier,the lower leakage current and higher breakdown voltage would be possible.
基金the National Natural Science Foundation of China(Grant Nos.61974111,11690042,and 61974115)the National Pre-research Foundation of China(Grant No.31512050402)the Fund of Innovation Center of Radiation Application,China(Grant No.KFZC2018040202).
文摘Two types of enhancement-mode(E-mode)AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors(MIS-HEMTs)with different gate insulators are fabricated on Si substrates.The HfO2 gate insulator and the Al2O3 gate insulator each with a thickness of 30 nm are grown by the plasma-enhanced atomic layer deposition(PEALD).The energy band diagrams of two types of dielectric MIS-HEMTs are compared.The breakdown voltage(VBR)of HfO2 dielectric layer and Al2O3 dielectric layer are 9.4 V and 15.9 V,respectively.With the same barrier thickness,the transconductance of MIS-HEMT with HfO2 is larger.The threshold voltage(Vth)of the HfO2 and Al2O3 MIS-HEMT are 2.0 V and 2.4 V,respectively,when the barrier layer thickness is 0 nm.The C-V characteristics are in good agreement with the Vth's transfer characteristics.As the barrier layer becomes thinner,the drain current density decreases sharply.Due to the dielectric/AlGaN interface is very close to the channel,the scattering of interface states will lead the electron mobility to decrease.The current collapse and the Ron of Al2O3 MIS-HEMT are smaller at the maximum gate voltage.As Al2O3 has excellent thermal stability and chemical stability,the interface state density of Al2O3/AlGaN is less than that of HfO2/AlGaN.
文摘In this letter,high power density AlGaN/GaN high electron-mobility transistors(HEMTs)on a freestanding GaN substrate are reported.An asymmetricΓ-shaped 500-nm gate with a field plate of 650 nm is introduced to improve microwave power performance.The breakdown voltage(BV)is increased to more than 200 V for the fabricated device with gate-to-source and gate-to-drain distances of 1.08 and 2.92μm.A record continuous-wave power density of 11.2 W/mm@10 GHz is realized with a drain bias of 70 V.The maximum oscillation frequency(f_(max))and unity current gain cut-off frequency(f_(t))of the AlGaN/GaN HEMTs exceed 30 and 20 GHz,respectively.The results demonstrate the potential of AlGaN/GaN HEMTs on freestanding GaN substrates for microwave power applications.
基金supported by the Key Program of the National Natural Science Foundation of China (Grant No. 62334002)the National Natural Science Foundation of China (Grant No. 62174008)。
文摘In this study, the effects of 1 MeV electron radiation on the D-mode GaN-based high electron mobility transistors(HEMTs) were investigated after different radiation doses. The changes in electrical properties of the device were obtained, and the related physical mechanisms were analyzed. It indicated that under the radiation dose of 5 × 10^(14) cm^(-2), the channel current cannot be completely pinched off even if the negative gate voltage was lower than the threshold voltage, and the gate leakage current increased significantly. The emission microscopy and scanning electron microscopy were used to determine the damage location. Besides, the radiation dose was adjusted ranging from 5 × 10^(12) to 1 × 10^(14) cm^(-2), and we noticed that the drain-source current increased and the threshold voltage presented slightly negative shift. By calculations, it suggested that the carrier density and electron mobility gradually increased. It provided a reference for the development of device radiation reinforcement technology.
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.
