The development of an AIGaN/GaN HEMT power MMIC on SI-SiC designed in microstrip technology is pres- ented. A recessed-gate and a field-plate are used in the device processing to improve the performance of the AIGaN/G...The development of an AIGaN/GaN HEMT power MMIC on SI-SiC designed in microstrip technology is pres- ented. A recessed-gate and a field-plate are used in the device processing to improve the performance of the AIGaN/GaN HEMTs. S-parameter measurements show that the frequency performance of the AIGaN/GaN HEMTs depends significantly on the operating voltage. Higher operating voltage is a key to higher power gain for the AIGaN/GaN HEMTs. The developed 2-stage power MMIC delivers an output power of more than 10W with over 12dB power gain across the band of 9-11GHz at a drain bias of 30V. Peak output power inside the band reaches 14.7W with a power gain of 13.7dB and a PAE of 23%. The MMIC chip size is only 2.0mm × 1. 1mm. This work shows superiority over previously reported X-band AIGaN/GaN HEMT power MMICs in output power per millimeter gate width and output power per unit chip size.展开更多
AlGaN/AlN/GaN high electron mobility transistor (HEMT) structures with a high-mobility GaN thin layer as a channel are grown on high resistive 6H-SiC substrates by metalorganic chemical vapor deposition. The HEMT st...AlGaN/AlN/GaN high electron mobility transistor (HEMT) structures with a high-mobility GaN thin layer as a channel are grown on high resistive 6H-SiC substrates by metalorganic chemical vapor deposition. The HEMT structure exhibits a typical two-dimensional electron gas (2DEG) mobility of 1944cm^2/(V·s) at room temperature and 11588cm^2/(V ·s) at 80K with almost equal 2DEG concentrations of about 1.03 × 10^13 cm^-2. High crystal quality of the HEMT structures is confirmed by triple-crystal X-ray diffraction analysis. Atomic force microscopy measurements reveal a smooth AlGaN surface with a root-mean-square roughness of 0.27nm for a scan area of 10μm × 10μm. HEMT devices with 0.8μm gate length and 1.2mm gate width are fabricated using the structures. A maximum drain current density of 957mA/mm and an extrinsic transconductance of 267mS/mm are obtained.展开更多
The growth, fabrication, and characterization of 0. 2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described. The unintentionally ...The growth, fabrication, and characterization of 0. 2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described. The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cmz^2(V· s) at an electron concentration of 1.52 × 10^16 cm^-3. The resistivity of the thick GaN buffer layer is greater than 10^8Ω· cm at room temperature. The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω□ with uniformity better than 96%. Devices of 0.2μm× 40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of 77GHz. The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W (2.23W/mm) and a linear gain of 13.3dB at 8GHz. The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.展开更多
With the principles of microwave circuits and semiconductor device physics, two microwave power device test circuits combined with a test fixture are designed and simulated, whose properties are evaluated by a paramet...With the principles of microwave circuits and semiconductor device physics, two microwave power device test circuits combined with a test fixture are designed and simulated, whose properties are evaluated by a parameter network analyzer within the frequency range from 3 to 8GHz. The simulation and experimental results verify that the test circuit with a radial stub is better than that without. As an example, a C-band AlGaN/GaN HEMT microwave power device is tested with the designed circuit and fixture. With a 5.4GHz microwave input signal,the maximum gain is 8.75dB,and the maximum output power is 33.2dBm.展开更多
Lattice matched InP based InAlAs/InGaAs HEMTs with 120GHz cutoff frequency are reported.These devices demonstrate excellent DC characteristics:the extrinsic transconductance of 600mS/mm,the threshold voltage of -1 ...Lattice matched InP based InAlAs/InGaAs HEMTs with 120GHz cutoff frequency are reported.These devices demonstrate excellent DC characteristics:the extrinsic transconductance of 600mS/mm,the threshold voltage of -1 2V,and the maximum current density of 500mA/mm.展开更多
Fabrication of enhancement-mode high electron mobility transistors on AlGaN/GaN heterostructures grown on sapphire substrates is reported. These devices with 1.2μm gate-length,4mm space between source and drain,and 1...Fabrication of enhancement-mode high electron mobility transistors on AlGaN/GaN heterostructures grown on sapphire substrates is reported. These devices with 1.2μm gate-length,4mm space between source and drain,and 15nm recessed-gate depth exhibit a maximum drain current of 332mA/mm at 3V, a maximum transconductance of 221mS/mm, a threshold voltage of 0.57V, ft of 5.2GHz, and fmax of 9.3GHz. A dielectric layer formed unintentionally during recessedgate etching is confirmed by contrasting the Schottky I-V characteristics of pre-etching and post-etching. The frequency characteristics and subthreshold characteristics of the devices are studied in detail.展开更多
A Si doped AlGaN/GaN HEMT structure with high Al content (x=43%) in the barrier layer is grown on sapphire substrate by RF-MBE.The structural and electrical properties of the heterostructure are investigated by the tr...A Si doped AlGaN/GaN HEMT structure with high Al content (x=43%) in the barrier layer is grown on sapphire substrate by RF-MBE.The structural and electrical properties of the heterostructure are investigated by the triple axis X-ray diffraction and Van der Pauw-Hall measurement,respectively.The observed prominent Bragg peaks of the GaN and AlGaN and the Hall results show that the structure is of high quality with smooth interface.The high 2DEG mobility in excess of 1260cm2/(V·s) is achieved with an electron density of 1.429×10 13cm -2 at 297K,corresponding to a sheet-density-mobility product of 1.8×10 16V -1·s -1.Devices based on the structure are fabricated and characterized.Better DC characteristics,maximum drain current of 1.0A/mm and extrinsic transconductance of 218mS/mm are obtained when compared with HEMTs fabricated using structures with lower Al mole fraction in the AlGaN barrier layer.The results suggest that the high Al content in the AlGaN barrier layer is promising in improving material electrical properties and device performance.展开更多
Lattice-matched In0.5 Ga0.47 As/In0.52 Al 0.48 As high electron mobility transistors (HEMTs) with a cutoff frequency (ft) as high as 218GHz are reported. This fT is the highest value ever reported for HEMTs in Chi...Lattice-matched In0.5 Ga0.47 As/In0.52 Al 0.48 As high electron mobility transistors (HEMTs) with a cutoff frequency (ft) as high as 218GHz are reported. This fT is the highest value ever reported for HEMTs in China. These devices also demonstrate excellent DC characteristics:the extrinsic transconductance is 980mS/mm and the maximum current density is 870mA/mm. The material structure and all the device fabrication technology in this work were developed by our group.展开更多
By epitaxial layer structure design and key fabrication process optimization,a lattice-matched InP-based In0.53Ga0.47 As-In0.52Al0.48As HEMT with an ultra high maximum oscillation frequency (fmax) of 183GHz was fab-...By epitaxial layer structure design and key fabrication process optimization,a lattice-matched InP-based In0.53Ga0.47 As-In0.52Al0.48As HEMT with an ultra high maximum oscillation frequency (fmax) of 183GHz was fab- ricated. The fmax is the highest value for HEMTs in China. Also, the devices are reported, including the device structure, the fabrication process, and the DC and RF performances.展开更多
A new method is used to simulate InGaAs/InP composite channel high electron mobility transistors (HEMTs). By coupling the hydrodynamic model and the density gradient model, the electron density distribution in the c...A new method is used to simulate InGaAs/InP composite channel high electron mobility transistors (HEMTs). By coupling the hydrodynamic model and the density gradient model, the electron density distribution in the channel in different electric fields is obtained. This method is faster and more robust than traditional meth- ods and should be applicable to other types of HEMTs simulations. A detailed study of the InGaAs/InP composite channel HEMTs is presented with the help of simulations.展开更多
AlGaN/GaN high electron mobility transistor (HEMT) materials are grown by RF plasma-assisted molecular beam epitaxy (RF-MBE) and HEMT devices are fabricated and characterized.The HEMT materials have a mobility of 1035...AlGaN/GaN high electron mobility transistor (HEMT) materials are grown by RF plasma-assisted molecular beam epitaxy (RF-MBE) and HEMT devices are fabricated and characterized.The HEMT materials have a mobility of 1035cm2/(V·s) at sheet electron concentration of 1.0×10 13cm -2at room temperature.For the devices fabricated using the materials,a maximum saturation drain-current density of 925mA/mm and a peak extrinsic transconductance of 186mS/mm are obtained on devices with gate length and width of 1μm and 80μm respectively.The f t,unit-current-gain frequency of the devices,is about 18.8GHz.展开更多
The molecular beam epitaxial growth of high quality epilayers on (100) InP substrate using a valve phosphorous cracker cell over a wide range of P/In BEP ratio (2.0-7.0) and growth rate (0.437 and 0. 791μm/h). ...The molecular beam epitaxial growth of high quality epilayers on (100) InP substrate using a valve phosphorous cracker cell over a wide range of P/In BEP ratio (2.0-7.0) and growth rate (0.437 and 0. 791μm/h). Experimental results show that electrical properties exhibit a pronounced dependence on growth parameters,which are growth rate, P/In BEP ratio, cracker zone temperature, and growth temperature. The parameters have been optimized carefully via the results of Hall measurements. For a typical sample, 77K electron mobility of 4.57 × 10^4 cm^2/(V · s) and electron concentration of 1.55×10^15 cm^-3 have been achieved with an epilayer thickness of 2.35μm at a growth temperature of 370℃ by using a cracking zone temperature of 850℃.展开更多
AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic (HD) systems. The influences of polarization charge and quantum effects are considered i...AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic (HD) systems. The influences of polarization charge and quantum effects are considered in this model. Then the two-dimensional conduction band and electron distribution, electron temperature characteristics, Id versus Vd and Id versus Vg, transfer characteristics and transconductance curves are obtained. Corresponding analysis and discussion based on the simulation results are subsequently given.展开更多
The current-voltage(I-V) characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, an...The current-voltage(I-V) characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, and the resulting curves are all similar in shape. When a voltage of about 560V is applied to the cBN crystal, the emitted light is visible to the naked eye in a dark room. We explain these phenomena by the space charge limited current and the electronic transition between the X and Г valleys of the conduction band.展开更多
The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS)...The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10-8 cm3/(molecules s) to 8.24×10-9 cm3/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ionmolecule reaction rate constants for the further reaction between Cl^- and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl- and CHCl3 are the first time detected using CD-IMS.展开更多
The monolithic integration of enhancement- and depletion-mode (E/D-mode) InGaP/AIGaAs/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) with a 1.0μm gate length is presented. Epilayers are grown on...The monolithic integration of enhancement- and depletion-mode (E/D-mode) InGaP/AIGaAs/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) with a 1.0μm gate length is presented. Epilayers are grown on SI GaAs substrates using MBE. For this structure, a mobility of 5410cm^2/(V · s) and a sheet density of 1.34 × 10^12 cm^-2 are achieved at room temperature. During the gate fabrication of E/D-mode PHEMTs,a novel twostep technology is applied. The devices with a gate dimension of 1μm × 100μm exhibit good DC and RF performances. Threshold voltages of 0. 2 and -0. 4V,maximum drain current densities of 300 and 340mA/mm,and extrinsic transconductances of 350 and 300mS/mm for E- and D-mode PHEMTs are obtained, respectively. The reverse gatedrain breakdown voltage is -14V for both E- and D-mode. Current-gain cutoff frequencies of 10. 3 and 12.4GHz and power-gain cutoff frequencies of 12.8 and 14.7GHz for E- and D-mode are reported, respectively.展开更多
An analytical model of electron mobility for strained-silicon channel nMOSFETs is proposed in this paper. The model deals directly with the strain tensor,and thus is independent of the manufacturing process. It is sui...An analytical model of electron mobility for strained-silicon channel nMOSFETs is proposed in this paper. The model deals directly with the strain tensor,and thus is independent of the manufacturing process. It is suitable for (100〉/ 〈110) channel nMOSFETs under biaxial or (100〉/〈 110 ) uniaxial stress and can be implemented in conventional device simulation tools .展开更多
The growth and device fabrication of AlGaN/GaN high electron mobility transistors (HEMTs) are carried out by using metal organic vapor phase epitaxy (MOVPE) system.Specially the performances of HEMT devices with diff...The growth and device fabrication of AlGaN/GaN high electron mobility transistors (HEMTs) are carried out by using metal organic vapor phase epitaxy (MOVPE) system.Specially the performances of HEMT devices with different thickness of AlGaN layer are compared.The device with thinner spacer layer exhibits better static performance.And a maximum saturation current density of 650mA/mm and a peak extrinsic transconductance of 100mS/mm are obtained from the devices with gate length of 1μm.展开更多
The Al 0.24Ga 0.76As/In 0.22Ga 0.78As single delta-doped PHEMT (SH-PHEMT) and double delta-doped PHEMT (DH-PHEMT) are fabricated and investigated.Based on the employment of double heterojunction,double del...The Al 0.24Ga 0.76As/In 0.22Ga 0.78As single delta-doped PHEMT (SH-PHEMT) and double delta-doped PHEMT (DH-PHEMT) are fabricated and investigated.Based on the employment of double heterojunction,double delta doped design,the DH-PHEMT can enhance the carrier confinement,increase the electron gas density,and improve the electron gas distribution,which is beneficial to the device performance.A high device linearity,high transconductance over a large gate voltage swing,high current drivability are found in DH-PHEMT.These improvements suggest that DH-PHEMT is more suitable for high linearity applications in microwave power device.展开更多
文摘The development of an AIGaN/GaN HEMT power MMIC on SI-SiC designed in microstrip technology is pres- ented. A recessed-gate and a field-plate are used in the device processing to improve the performance of the AIGaN/GaN HEMTs. S-parameter measurements show that the frequency performance of the AIGaN/GaN HEMTs depends significantly on the operating voltage. Higher operating voltage is a key to higher power gain for the AIGaN/GaN HEMTs. The developed 2-stage power MMIC delivers an output power of more than 10W with over 12dB power gain across the band of 9-11GHz at a drain bias of 30V. Peak output power inside the band reaches 14.7W with a power gain of 13.7dB and a PAE of 23%. The MMIC chip size is only 2.0mm × 1. 1mm. This work shows superiority over previously reported X-band AIGaN/GaN HEMT power MMICs in output power per millimeter gate width and output power per unit chip size.
文摘AlGaN/AlN/GaN high electron mobility transistor (HEMT) structures with a high-mobility GaN thin layer as a channel are grown on high resistive 6H-SiC substrates by metalorganic chemical vapor deposition. The HEMT structure exhibits a typical two-dimensional electron gas (2DEG) mobility of 1944cm^2/(V·s) at room temperature and 11588cm^2/(V ·s) at 80K with almost equal 2DEG concentrations of about 1.03 × 10^13 cm^-2. High crystal quality of the HEMT structures is confirmed by triple-crystal X-ray diffraction analysis. Atomic force microscopy measurements reveal a smooth AlGaN surface with a root-mean-square roughness of 0.27nm for a scan area of 10μm × 10μm. HEMT devices with 0.8μm gate length and 1.2mm gate width are fabricated using the structures. A maximum drain current density of 957mA/mm and an extrinsic transconductance of 267mS/mm are obtained.
文摘The growth, fabrication, and characterization of 0. 2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described. The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cmz^2(V· s) at an electron concentration of 1.52 × 10^16 cm^-3. The resistivity of the thick GaN buffer layer is greater than 10^8Ω· cm at room temperature. The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω□ with uniformity better than 96%. Devices of 0.2μm× 40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of 77GHz. The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W (2.23W/mm) and a linear gain of 13.3dB at 8GHz. The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.
文摘With the principles of microwave circuits and semiconductor device physics, two microwave power device test circuits combined with a test fixture are designed and simulated, whose properties are evaluated by a parameter network analyzer within the frequency range from 3 to 8GHz. The simulation and experimental results verify that the test circuit with a radial stub is better than that without. As an example, a C-band AlGaN/GaN HEMT microwave power device is tested with the designed circuit and fixture. With a 5.4GHz microwave input signal,the maximum gain is 8.75dB,and the maximum output power is 33.2dBm.
文摘Lattice matched InP based InAlAs/InGaAs HEMTs with 120GHz cutoff frequency are reported.These devices demonstrate excellent DC characteristics:the extrinsic transconductance of 600mS/mm,the threshold voltage of -1 2V,and the maximum current density of 500mA/mm.
基金the Key Programof the National Natural Science Foundation of China(No.60736033)~~
文摘Fabrication of enhancement-mode high electron mobility transistors on AlGaN/GaN heterostructures grown on sapphire substrates is reported. These devices with 1.2μm gate-length,4mm space between source and drain,and 15nm recessed-gate depth exhibit a maximum drain current of 332mA/mm at 3V, a maximum transconductance of 221mS/mm, a threshold voltage of 0.57V, ft of 5.2GHz, and fmax of 9.3GHz. A dielectric layer formed unintentionally during recessedgate etching is confirmed by contrasting the Schottky I-V characteristics of pre-etching and post-etching. The frequency characteristics and subthreshold characteristics of the devices are studied in detail.
文摘A Si doped AlGaN/GaN HEMT structure with high Al content (x=43%) in the barrier layer is grown on sapphire substrate by RF-MBE.The structural and electrical properties of the heterostructure are investigated by the triple axis X-ray diffraction and Van der Pauw-Hall measurement,respectively.The observed prominent Bragg peaks of the GaN and AlGaN and the Hall results show that the structure is of high quality with smooth interface.The high 2DEG mobility in excess of 1260cm2/(V·s) is achieved with an electron density of 1.429×10 13cm -2 at 297K,corresponding to a sheet-density-mobility product of 1.8×10 16V -1·s -1.Devices based on the structure are fabricated and characterized.Better DC characteristics,maximum drain current of 1.0A/mm and extrinsic transconductance of 218mS/mm are obtained when compared with HEMTs fabricated using structures with lower Al mole fraction in the AlGaN barrier layer.The results suggest that the high Al content in the AlGaN barrier layer is promising in improving material electrical properties and device performance.
文摘Lattice-matched In0.5 Ga0.47 As/In0.52 Al 0.48 As high electron mobility transistors (HEMTs) with a cutoff frequency (ft) as high as 218GHz are reported. This fT is the highest value ever reported for HEMTs in China. These devices also demonstrate excellent DC characteristics:the extrinsic transconductance is 980mS/mm and the maximum current density is 870mA/mm. The material structure and all the device fabrication technology in this work were developed by our group.
文摘By epitaxial layer structure design and key fabrication process optimization,a lattice-matched InP-based In0.53Ga0.47 As-In0.52Al0.48As HEMT with an ultra high maximum oscillation frequency (fmax) of 183GHz was fab- ricated. The fmax is the highest value for HEMTs in China. Also, the devices are reported, including the device structure, the fabrication process, and the DC and RF performances.
文摘A new method is used to simulate InGaAs/InP composite channel high electron mobility transistors (HEMTs). By coupling the hydrodynamic model and the density gradient model, the electron density distribution in the channel in different electric fields is obtained. This method is faster and more robust than traditional meth- ods and should be applicable to other types of HEMTs simulations. A detailed study of the InGaAs/InP composite channel HEMTs is presented with the help of simulations.
文摘AlGaN/GaN high electron mobility transistor (HEMT) materials are grown by RF plasma-assisted molecular beam epitaxy (RF-MBE) and HEMT devices are fabricated and characterized.The HEMT materials have a mobility of 1035cm2/(V·s) at sheet electron concentration of 1.0×10 13cm -2at room temperature.For the devices fabricated using the materials,a maximum saturation drain-current density of 925mA/mm and a peak extrinsic transconductance of 186mS/mm are obtained on devices with gate length and width of 1μm and 80μm respectively.The f t,unit-current-gain frequency of the devices,is about 18.8GHz.
文摘The molecular beam epitaxial growth of high quality epilayers on (100) InP substrate using a valve phosphorous cracker cell over a wide range of P/In BEP ratio (2.0-7.0) and growth rate (0.437 and 0. 791μm/h). Experimental results show that electrical properties exhibit a pronounced dependence on growth parameters,which are growth rate, P/In BEP ratio, cracker zone temperature, and growth temperature. The parameters have been optimized carefully via the results of Hall measurements. For a typical sample, 77K electron mobility of 4.57 × 10^4 cm^2/(V · s) and electron concentration of 1.55×10^15 cm^-3 have been achieved with an epilayer thickness of 2.35μm at a growth temperature of 370℃ by using a cracking zone temperature of 850℃.
文摘AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic (HD) systems. The influences of polarization charge and quantum effects are considered in this model. Then the two-dimensional conduction band and electron distribution, electron temperature characteristics, Id versus Vd and Id versus Vg, transfer characteristics and transconductance curves are obtained. Corresponding analysis and discussion based on the simulation results are subsequently given.
文摘The current-voltage(I-V) characteristics of cBN crystal sandwiched between two metallic electrodes are measured and found to be nonlinear. Over 20 samples are measured at room temperature with various electrodes, and the resulting curves are all similar in shape. When a voltage of about 560V is applied to the cBN crystal, the emitted light is visible to the naked eye in a dark room. We explain these phenomena by the space charge limited current and the electronic transition between the X and Г valleys of the conduction band.
基金ACKNOWLEDGMENTS The work was support by the National Natural Science Foundation of China (No.20707025 and No.20907054) and the Excellent Youth Foundation of Anhui Province Scientific Committee (No.06045098).
文摘The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10-8 cm3/(molecules s) to 8.24×10-9 cm3/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ionmolecule reaction rate constants for the further reaction between Cl^- and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl- and CHCl3 are the first time detected using CD-IMS.
文摘The monolithic integration of enhancement- and depletion-mode (E/D-mode) InGaP/AIGaAs/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) with a 1.0μm gate length is presented. Epilayers are grown on SI GaAs substrates using MBE. For this structure, a mobility of 5410cm^2/(V · s) and a sheet density of 1.34 × 10^12 cm^-2 are achieved at room temperature. During the gate fabrication of E/D-mode PHEMTs,a novel twostep technology is applied. The devices with a gate dimension of 1μm × 100μm exhibit good DC and RF performances. Threshold voltages of 0. 2 and -0. 4V,maximum drain current densities of 300 and 340mA/mm,and extrinsic transconductances of 350 and 300mS/mm for E- and D-mode PHEMTs are obtained, respectively. The reverse gatedrain breakdown voltage is -14V for both E- and D-mode. Current-gain cutoff frequencies of 10. 3 and 12.4GHz and power-gain cutoff frequencies of 12.8 and 14.7GHz for E- and D-mode are reported, respectively.
文摘An analytical model of electron mobility for strained-silicon channel nMOSFETs is proposed in this paper. The model deals directly with the strain tensor,and thus is independent of the manufacturing process. It is suitable for (100〉/ 〈110) channel nMOSFETs under biaxial or (100〉/〈 110 ) uniaxial stress and can be implemented in conventional device simulation tools .
文摘The growth and device fabrication of AlGaN/GaN high electron mobility transistors (HEMTs) are carried out by using metal organic vapor phase epitaxy (MOVPE) system.Specially the performances of HEMT devices with different thickness of AlGaN layer are compared.The device with thinner spacer layer exhibits better static performance.And a maximum saturation current density of 650mA/mm and a peak extrinsic transconductance of 100mS/mm are obtained from the devices with gate length of 1μm.
文摘The Al 0.24Ga 0.76As/In 0.22Ga 0.78As single delta-doped PHEMT (SH-PHEMT) and double delta-doped PHEMT (DH-PHEMT) are fabricated and investigated.Based on the employment of double heterojunction,double delta doped design,the DH-PHEMT can enhance the carrier confinement,increase the electron gas density,and improve the electron gas distribution,which is beneficial to the device performance.A high device linearity,high transconductance over a large gate voltage swing,high current drivability are found in DH-PHEMT.These improvements suggest that DH-PHEMT is more suitable for high linearity applications in microwave power device.