The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors (HEMTs) is investigated by temperature-dependent current-voltage (T-I-V) measurements from 300 K to 473 K. The ideality factor and ...The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors (HEMTs) is investigated by temperature-dependent current-voltage (T-I-V) measurements from 300 K to 473 K. The ideality factor and barrier height determined based on the thermionic emission (TE) theory are found to be strong functions of temperature, while present a great deviation from the theoretical value, which can be expounded by the barrier height inhomogeneities. In order to determine the forward current transport mechanisms, the experimental data are analyzed using numerical fitting method, considering the temperature-dependent series resistance. It is observed that the current flow at room temperature can be attributed to the tunneling mechanism, while thermionic emission current gains a growing proportion with an increase in temperature. Finally, the effective barrier height is derived based on the extracted thermionic emission component, and an evaluation of the density of dislocations is made from the I-V characteristics, giving a value of 1.49 × 10^7 cm^-2.展开更多
L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正...L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。展开更多
As the front-end preamplifiers in optical receivers, transimpedance amplifiers (TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time,...As the front-end preamplifiers in optical receivers, transimpedance amplifiers (TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range (DR) to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.展开更多
A fully integrated Ku-band voltage controlled oscillator (VCO) is presented in an InGaP/GaAs hetero- junction bipolar transistor (HBT) technology. To achieve the wide tuning range (TR), the VCO employs a Colpitt...A fully integrated Ku-band voltage controlled oscillator (VCO) is presented in an InGaP/GaAs hetero- junction bipolar transistor (HBT) technology. To achieve the wide tuning range (TR), the VCO employs a Colpitts configuration, and the VCO simultaneously achieves high output power. The implemented VCO demonstrates an oscillation frequency range from 12.82 to 14.97 GHz, a frequency TR of 15.47%, an output power from 0.31 to 6.46 dBm, and a phase noise of -94.9 dBc/Hz at 1 MHz offset from 13.9 GHz center frequency. The VCO con- sumes 52.75 mW from 5 V supply and occupies an area of 0.81 × 0.78 mm2. Finally, the figures-of-merit for VCOs is discussed.展开更多
The formation of low-resistance Ohmic contacts in Ga_(2)O_(3) is crucial for high-performance electronic devices. Conventionally, a titanium/gold(Ti/Au) electrode is rapidly annealed to achieve Ohmic contacts, resulti...The formation of low-resistance Ohmic contacts in Ga_(2)O_(3) is crucial for high-performance electronic devices. Conventionally, a titanium/gold(Ti/Au) electrode is rapidly annealed to achieve Ohmic contacts, resulting in mutual diffusion of atoms at the interface. However, the specific role of diffusing elements in Ohmic contact formation remains unclear.In this work, we investigate the contribution of oxygen atom diffusion to the formation of Ohmic contacts in Ga_(2)O_(3). We prepare a Ti/Au electrode on a single crystal substrate and conduct a series of electrical and structural characterizations.Using density functional theory, we construct a model of the interface and calculate the charge density, partial density of states, planar electrostatic potential energy, and I–V characteristics. Our results demonstrate that the oxygen atom diffusion effectively reduces the interface barrier, leading to low-resistance Ohmic contacts in Ga_(2)O_(3). These findings provide valuable insights into the underlying mechanisms of Ohmic contact formation and highlight the importance of considering the oxygen atom diffusion in the design of Ga_(2)O_(3)-based electronic devices.展开更多
The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive positi...The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.展开更多
High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm...High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm,the dual-Schottky-junctions coupling device(DSCD)was fabricated.Due to the electrically floating Ga_(2)O_(3)nanobelt region coupling with the double Schottky-junctions,the current I_(S2)increases firstly and rapidly reaches into saturation as increase the voltage V_(S2).The saturation current is about 10 pA,which is two orders of magnitude lower than that of a single Schottky-junction.In the case of solar-blind ultraviolet(UV)light irradiation,the photogenerated electrons further aggravate the coupling physical mechanism in device.I_(S2)increases as the intensity of UV light increases.Under the UV light of 1820μW/cm^(2),I_(S2)quickly enters the saturation state.At V_(S2)=10 V,photo-to-dark current ratio(PDCR)of the device reaches more than 104,the external quantum efficiency(EQE)is 1.6×10^(3)%,and the detectivity(D*)is 7.5×10^(12)Jones.In addition,the device has a very short rise and decay times of 25−54 ms under different positive and negative bias.DSCD shows unique electrical and optical control characteristics,which will open a new way for the application of nanobelt-based devices.展开更多
1 Introduction Ⅲ-nitride wide bandgap semiconductors, such as GaN, InN, AIN and their ternary or quaternary alloy components, are wholly-component direct band gap materials with a full adjustable band gap (0.63-6.2e...1 Introduction Ⅲ-nitride wide bandgap semiconductors, such as GaN, InN, AIN and their ternary or quaternary alloy components, are wholly-component direct band gap materials with a full adjustable band gap (0.63-6.2eV), strong polarization, high temperature resistant, anti-radiation, and can be achieved with low-dimensional quantum structures. Furthermore, it is the only one semiconductor material system that covers ultraviolet to infrared wavelength band. Therefore, a lot of attention has been paid to them. Through unremitting efforts, blue-green light-emitting diodes (LEDs) based on InGaN/GaN quantum well materials with low in composition have been developed and successfully industrialized. Their applications in the fields of the solid-state lighting and flat-panel displays are profoundly changing people's lives. In addition, high power electron mobility transistor devices (HEMT) based on low A1 content AIGaN/GaN heterostructure have significant applications in the fields of X-band radar and civilian communications~ which is profoundly affecting the national security situation and the world's strategic pattern.展开更多
针对空间应用,开展SiC MOSFET单粒子效应试验研究。在加速器上用重离子辐照1200 V SiC MOSFET,离子线性能量传输(LET)在0.26~118 MeV·cm^(2)/mg之间,辐照中被试器件加50~600 V静态漏源偏置电压、栅源短接,实时测量电特性,进行辐照...针对空间应用,开展SiC MOSFET单粒子效应试验研究。在加速器上用重离子辐照1200 V SiC MOSFET,离子线性能量传输(LET)在0.26~118 MeV·cm^(2)/mg之间,辐照中被试器件加50~600 V静态漏源偏置电压、栅源短接,实时测量电特性,进行辐照后栅应力(PIGS)测试。试验结果发现,50~100 V偏置电压下,离子引起瞬态电流,PIGS测试栅失效。分析认为离子引起栅氧化物潜在损伤,PIGS测试过程中,潜在损伤进一步退化导致栅失效。氧化物潜在损伤不仅与辐照偏置电压有关,还与入射离子LET和注量有关。PIGS测试需要的栅应力时间与潜在损伤程度有关,可超过300 s。并给出了电荷累积损伤模型。模型进行SiC MOSFET单粒子效应评估时,应考虑离子引起栅氧化物潜在损伤的影响,需根据轨道和任务周期确定试验离子注量,根据应用情况确定辐照偏置电压,并评估确定PIGS测试栅应力时间。展开更多
高阻断电压、大功率密度、高转化效率是电力电子器件技术持续追求的目标,基于4H-SiC优异的材料特性,在电力电子器件应用方面具有广阔的发展前景。围绕SiC MOSFET器件对外延材料的需求,介绍了国内外主流的SiC外延设备及国产SiC衬底的发展...高阻断电压、大功率密度、高转化效率是电力电子器件技术持续追求的目标,基于4H-SiC优异的材料特性,在电力电子器件应用方面具有广阔的发展前景。围绕SiC MOSFET器件对外延材料的需求,介绍了国内外主流的SiC外延设备及国产SiC衬底的发展,并重点介绍了宽禁带半导体电力电子器件国家重点实验室在国产150 mm(6英寸)SiC衬底上的高速外延技术进展。通过关键技术攻关,实现了150 mm SiC外延材料表面缺陷密度≤0.5 cm-2,BPD缺陷密度≤0.1 cm-2,片内掺杂浓度不均匀性≤5%,片内厚度不均匀性≤1%。基于自主外延材料,实现了650~1200 V SiC MOSFET产品商业化以及6.5~15 kV高压SiC MOSFET器件的产品定型。展开更多
基金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 of China(Grant No.ZHD201206)
文摘The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors (HEMTs) is investigated by temperature-dependent current-voltage (T-I-V) measurements from 300 K to 473 K. The ideality factor and barrier height determined based on the thermionic emission (TE) theory are found to be strong functions of temperature, while present a great deviation from the theoretical value, which can be expounded by the barrier height inhomogeneities. In order to determine the forward current transport mechanisms, the experimental data are analyzed using numerical fitting method, considering the temperature-dependent series resistance. It is observed that the current flow at room temperature can be attributed to the tunneling mechanism, while thermionic emission current gains a growing proportion with an increase in temperature. Finally, the effective barrier height is derived based on the extracted thermionic emission component, and an evaluation of the density of dislocations is made from the I-V characteristics, giving a value of 1.49 × 10^7 cm^-2.
文摘L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。
基金supported by the National Natural Science Foundation of China(Nos.61376033,61006028)the National High-Tech Program of China(Nos.2012AA012302,2013AA014103)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory
文摘As the front-end preamplifiers in optical receivers, transimpedance amplifiers (TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range (DR) to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter, an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dBΩ with the -3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to 10 mA. The output voltage noise is less than 48.23 nV/√Hz within the -3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 μm 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.
基金Project supported by the National Basic Research Program of China(No.2010CBxxxx05)the Advance Research Project of China(No.51308xxxx06)+2 种基金the Advance Research Foundation of China(No.9140A08xxxx11DZ111)Doctoral Scientific Research Foundation of Henan University of Science and Technology(No.400613480011)the Foundation of He’nan Educational Commettee(No.15A510001)
文摘A fully integrated Ku-band voltage controlled oscillator (VCO) is presented in an InGaP/GaAs hetero- junction bipolar transistor (HBT) technology. To achieve the wide tuning range (TR), the VCO employs a Colpitts configuration, and the VCO simultaneously achieves high output power. The implemented VCO demonstrates an oscillation frequency range from 12.82 to 14.97 GHz, a frequency TR of 15.47%, an output power from 0.31 to 6.46 dBm, and a phase noise of -94.9 dBc/Hz at 1 MHz offset from 13.9 GHz center frequency. The VCO con- sumes 52.75 mW from 5 V supply and occupies an area of 0.81 × 0.78 mm2. Finally, the figures-of-merit for VCOs is discussed.
基金Projects supported by the National Natural Science Foundation of China (Grant Nos.61874084,61974119,and U21A20501)。
文摘The formation of low-resistance Ohmic contacts in Ga_(2)O_(3) is crucial for high-performance electronic devices. Conventionally, a titanium/gold(Ti/Au) electrode is rapidly annealed to achieve Ohmic contacts, resulting in mutual diffusion of atoms at the interface. However, the specific role of diffusing elements in Ohmic contact formation remains unclear.In this work, we investigate the contribution of oxygen atom diffusion to the formation of Ohmic contacts in Ga_(2)O_(3). We prepare a Ti/Au electrode on a single crystal substrate and conduct a series of electrical and structural characterizations.Using density functional theory, we construct a model of the interface and calculate the charge density, partial density of states, planar electrostatic potential energy, and I–V characteristics. Our results demonstrate that the oxygen atom diffusion effectively reduces the interface barrier, leading to low-resistance Ohmic contacts in Ga_(2)O_(3). These findings provide valuable insights into the underlying mechanisms of Ohmic contact formation and highlight the importance of considering the oxygen atom diffusion in the design of Ga_(2)O_(3)-based electronic devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61574171,61704127,11875229,51872251,and 12027813)。
文摘The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.
基金supported by Natural Science Basic Research Program in Shaanxi Province of China(No.2023-JCYB-574)National Natural Science Foundation of China(No.62204203).
文摘High qualityβ-Ga_(2)O_(3)single crystal nanobelts with length of 2−3 mm and width from tens of microns to 132μm were synthesized by carbothermal reduction method.Based on the grown nanobelt with the length of 600μm,the dual-Schottky-junctions coupling device(DSCD)was fabricated.Due to the electrically floating Ga_(2)O_(3)nanobelt region coupling with the double Schottky-junctions,the current I_(S2)increases firstly and rapidly reaches into saturation as increase the voltage V_(S2).The saturation current is about 10 pA,which is two orders of magnitude lower than that of a single Schottky-junction.In the case of solar-blind ultraviolet(UV)light irradiation,the photogenerated electrons further aggravate the coupling physical mechanism in device.I_(S2)increases as the intensity of UV light increases.Under the UV light of 1820μW/cm^(2),I_(S2)quickly enters the saturation state.At V_(S2)=10 V,photo-to-dark current ratio(PDCR)of the device reaches more than 104,the external quantum efficiency(EQE)is 1.6×10^(3)%,and the detectivity(D*)is 7.5×10^(12)Jones.In addition,the device has a very short rise and decay times of 25−54 ms under different positive and negative bias.DSCD shows unique electrical and optical control characteristics,which will open a new way for the application of nanobelt-based devices.
文摘1 Introduction Ⅲ-nitride wide bandgap semiconductors, such as GaN, InN, AIN and their ternary or quaternary alloy components, are wholly-component direct band gap materials with a full adjustable band gap (0.63-6.2eV), strong polarization, high temperature resistant, anti-radiation, and can be achieved with low-dimensional quantum structures. Furthermore, it is the only one semiconductor material system that covers ultraviolet to infrared wavelength band. Therefore, a lot of attention has been paid to them. Through unremitting efforts, blue-green light-emitting diodes (LEDs) based on InGaN/GaN quantum well materials with low in composition have been developed and successfully industrialized. Their applications in the fields of the solid-state lighting and flat-panel displays are profoundly changing people's lives. In addition, high power electron mobility transistor devices (HEMT) based on low A1 content AIGaN/GaN heterostructure have significant applications in the fields of X-band radar and civilian communications~ which is profoundly affecting the national security situation and the world's strategic pattern.
文摘针对空间应用,开展SiC MOSFET单粒子效应试验研究。在加速器上用重离子辐照1200 V SiC MOSFET,离子线性能量传输(LET)在0.26~118 MeV·cm^(2)/mg之间,辐照中被试器件加50~600 V静态漏源偏置电压、栅源短接,实时测量电特性,进行辐照后栅应力(PIGS)测试。试验结果发现,50~100 V偏置电压下,离子引起瞬态电流,PIGS测试栅失效。分析认为离子引起栅氧化物潜在损伤,PIGS测试过程中,潜在损伤进一步退化导致栅失效。氧化物潜在损伤不仅与辐照偏置电压有关,还与入射离子LET和注量有关。PIGS测试需要的栅应力时间与潜在损伤程度有关,可超过300 s。并给出了电荷累积损伤模型。模型进行SiC MOSFET单粒子效应评估时,应考虑离子引起栅氧化物潜在损伤的影响,需根据轨道和任务周期确定试验离子注量,根据应用情况确定辐照偏置电压,并评估确定PIGS测试栅应力时间。
文摘高阻断电压、大功率密度、高转化效率是电力电子器件技术持续追求的目标,基于4H-SiC优异的材料特性,在电力电子器件应用方面具有广阔的发展前景。围绕SiC MOSFET器件对外延材料的需求,介绍了国内外主流的SiC外延设备及国产SiC衬底的发展,并重点介绍了宽禁带半导体电力电子器件国家重点实验室在国产150 mm(6英寸)SiC衬底上的高速外延技术进展。通过关键技术攻关,实现了150 mm SiC外延材料表面缺陷密度≤0.5 cm-2,BPD缺陷密度≤0.1 cm-2,片内掺杂浓度不均匀性≤5%,片内厚度不均匀性≤1%。基于自主外延材料,实现了650~1200 V SiC MOSFET产品商业化以及6.5~15 kV高压SiC MOSFET器件的产品定型。