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
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
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
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
[Objective] The aim was to better research the function and action mode of High Mobility Group B （HMGB） proteins in higher plants. [Method] At2G33450,At5G23405 and At5G23420 genes of HMGB protein family in Arabidops...[Objective] The aim was to better research the function and action mode of High Mobility Group B （HMGB） proteins in higher plants. [Method] At2G33450,At5G23405 and At5G23420 genes of HMGB protein family in Arabidopsis thaliana were cloned by the use of RT-PCR method,and the expression of these three proteins in E.coli and Arabidopsis thaliana were detected by using SDS-PAGE,Northern blot and subcellular localization methods. [Result] The results showed that the molecular weights of the three proteins were 17.5,17.0 and 27.0 kD respectively,and the expression levels of the proteins in Arabidopsis thaliana were At5G23420At5G23405At2G33450. In addition,all the three proteins were located in nucleus. [Conclusion] The study will provide a basis for the further research on the biological function of HMGB proteins in higher plants.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
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
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
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
[Objective] The aim was to study the expression of Arabidopsis gene A/2G34450 in Pichia pastoris and to obtain recombinant Arabidopsis HMGB protein. [Method] The At2G34450 gene was cloned into yeast expression vector ...[Objective] The aim was to study the expression of Arabidopsis gene A/2G34450 in Pichia pastoris and to obtain recombinant Arabidopsis HMGB protein. [Method] The At2G34450 gene was cloned into yeast expression vector pPIC9K containing AOXl promoter and the sequences of secreting α-signal peptides. Recombinant plasmid was linearized by Sal l and transformed into P. pastoris GSl15 competent cells by electroporation. Positive integrated clones were screened out, and the At2G34450 protein was expressed under the induction of methanol. [Result] The At2G34450 protein was expressed in yeast medium through methanol induction. SDS-PAGE results showed that recombination product was At2G34450 protein. [Conclusion] At2G34450 protein was successfully expressed in the P. pastoris system for the first time, which paves a direct path to further research on the functions of HMGB family members.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[Objective] The aim was to better research the function and action mode of High Mobility Group B （HMGB） proteins in higher plants. [Method] At2G33450,At5G23405 and At5G23420 genes of HMGB protein family in Arabidopsis thaliana were cloned by the use of RT-PCR method,and the expression of these three proteins in E.coli and Arabidopsis thaliana were detected by using SDS-PAGE,Northern blot and subcellular localization methods. [Result] The results showed that the molecular weights of the three proteins were 17.5,17.0 and 27.0 kD respectively,and the expression levels of the proteins in Arabidopsis thaliana were At5G23420At5G23405At2G33450. In addition,all the three proteins were located in nucleus. [Conclusion] The study will provide a basis for the further research on the biological function of HMGB proteins in higher plants.
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.
基金Supported by Scientific Research Start-up Fund for Doctors of Liaocheng University(31805)~~
文摘[Objective] The aim was to study the expression of Arabidopsis gene A/2G34450 in Pichia pastoris and to obtain recombinant Arabidopsis HMGB protein. [Method] The At2G34450 gene was cloned into yeast expression vector pPIC9K containing AOXl promoter and the sequences of secreting α-signal peptides. Recombinant plasmid was linearized by Sal l and transformed into P. pastoris GSl15 competent cells by electroporation. Positive integrated clones were screened out, and the At2G34450 protein was expressed under the induction of methanol. [Result] The At2G34450 protein was expressed in yeast medium through methanol induction. SDS-PAGE results showed that recombination product was At2G34450 protein. [Conclusion] At2G34450 protein was successfully expressed in the P. pastoris system for the first time, which paves a direct path to further research on the functions of HMGB family members.
