通过商用半导体模拟器MEDICI对700 V 4H-SiC晶闸管开通特性进行了模拟研究。模拟结果表明阳极电压小于100 V时,开通过程符合扩散模型,电压更高时,开通时间随阳极电压升高而迅速下降,符合场开通机制。不同于Si及GaAs晶闸管,SiC晶闸管p型...通过商用半导体模拟器MEDICI对700 V 4H-SiC晶闸管开通特性进行了模拟研究。模拟结果表明阳极电压小于100 V时,开通过程符合扩散模型,电压更高时,开通时间随阳极电压升高而迅速下降,符合场开通机制。不同于Si及GaAs晶闸管,SiC晶闸管p型耐压层中浅能级杂质Al使得其开通时间随温度的升高而降低。较厚的基区使得电导调制效应只发生在发射区与基区边界一个范围之内,随着温度的升高,其余部分的载流子数目指数增加,压降指数减小。开通时间随着门极触发电流的加大而逐渐缩短,减小到一定程度时,减小速度明显变缓。展开更多
本文基于SMIC 28 nm CMOS工艺设计了一款应用于超宽带协议的具有带外噪声抑制功能的全集成低噪声放大器(Low Noise Amplifier,LNA),并提出了一种新型的LC串并联两级滤波结构.通过利用滤波器极点补偿LNA带内增益的设计方法,合理设计滤波...本文基于SMIC 28 nm CMOS工艺设计了一款应用于超宽带协议的具有带外噪声抑制功能的全集成低噪声放大器(Low Noise Amplifier,LNA),并提出了一种新型的LC串并联两级滤波结构.通过利用滤波器极点补偿LNA带内增益的设计方法,合理设计滤波负载等效电路的极点,使其略高于零点频率,在保证了LNA通带增益和噪声的情况下提高了滤波深度.对所设计的LNA进行了EMX建模及仿真验证.结果表明,该LNA在6.5~10 GHz的工作频带内,S_(21)高达21.17~25.28 d B,S_(11)小于-10.58 d B;S_(22)小于-11.20 d B,带内噪声系数仅为2.14~2.51 d B;带阻滤波器在5.8 GHz处可提供-35.45 d B的噪声抑制;在0.9 V供电电压下,LNA的静态功耗仅为9.36 m W.展开更多
SiCGe ternary alloys have been grown on SiC by hot-wall low-pressure chemical vapour deposition. It has been found that the samples cxhibit an island configuration, and the island growth of SiCGe epilayer depends on t...SiCGe ternary alloys have been grown on SiC by hot-wall low-pressure chemical vapour deposition. It has been found that the samples cxhibit an island configuration, and the island growth of SiCGe epilayer depends on the processing parameters such as the growth temperature. When the growth temperature is comparatively low, the epilayer has two types of islands： onc is spherical island; another is cascading triangular island. With the increase of the growth temperature, the islands change from spherical to cascading triangular mode. The size and density of the islands depend on the growth duration and GeH4 flow-rate. A longer growth time and a larger GeH4 flow-rate can increase the size and density of the island in thc initial stage of the epitaxy. In our case, The optimal growth for a high density of uniform islands occurred at a growth temperature of 1100℃ for l-minute growth, with 10 SCCM GeH4, resulting in a narrow size distribution （about 30nm diameter） and high density （about 3.5 ×10^10 dots/cm2）. The growth follows Stranski- Krastanov modc （2D to 3D modc）, both of the islands and the 2D growth layer have face-centred cubic structure, and the critical thickness of the 2D growth layer is only 2.5 nm.展开更多
The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play t...The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play the role of an light absorbing layer. This paper reports on Si films heteroepitaxially grown on the Si face of （0001） n-type 6H-SiC substrates and the use of B2H6 as a dopant for p-Si grown at temperatures in a range of 700-950℃. X-ray diffraction （XRD） analysis and transmission electron microscopy （TEM） tests have demonstrated that the samples prepared at the temperatures ranged from 850℃ to 900℃ are characterized as monocrystalline silicon. The rocking XRD curves show a well symmetry with FWHM of 0.4339° Omega. Twin crystals and stacking faults observed in the epitaxial layers might be responsible for widening of the rocking curves. Dependence of the crystal structure and surface topography on growth temperature is discussed based on the experimental results. The energy band structure and rectifying characteristics of the Si/SiC heterojunctions are also preliminarily tested.展开更多
The energy-band structure and non-ultraviolet photoelectric properties of a Ni/n-Si/N^(+)-SiC isotype heterostruc-ture Schottky photodiode are simulated by using Silvaco-Atlas.There are energy offsets in the conductio...The energy-band structure and non-ultraviolet photoelectric properties of a Ni/n-Si/N^(+)-SiC isotype heterostruc-ture Schottky photodiode are simulated by using Silvaco-Atlas.There are energy offsets in the conduction and valance band of the heterojunction,which are about 0.09eV and 1.79eV,respectively.The non-UV photodiode with this structure is fabricated on a 6H-SiC(0001)substrate.𝐾J–V𝑊measurements indicate that the device has good rectifying behavior with a rectification ratio up to 200 at 5V,and the turn-on voltage is about 0.7V.Under non-ultraviolet illumination of 0.6W/cm^(2),the device demonstrates a significant photoelectric response with a photocurrent density of 2.9mA/cm^(2)and an open-circuit voltage of 63.0mV.Non-ultraviolet operation of the SiC-based photoelectric device is initially realized.展开更多
6H-SiC （1010） surface and Si （220）/6H-SIC （1010） interface with different stacking sites are investigated using first-principles calculations. Surface energies of 6H-SiC （1010） （case I, case II, and case III...6H-SiC （1010） surface and Si （220）/6H-SIC （1010） interface with different stacking sites are investigated using first-principles calculations. Surface energies of 6H-SiC （1010） （case I, case II, and case III） are firstly studied and the surface calculation results show that case II and case III are more stable than case I. Then, the adhesion energies, fracture toughness values, interfacial energies, densities of states, and electronic structures of Si （220）/6H-SIC （1010） interfaces for three stacking models （AM, BM, and CM） are calculated. The CM model has the highest adhesion energy and the lowest interracial energy, suggesting that the CM is stronger and more thermodynamically stable than AM and BM. Densities of states and the total charge densities give evidence that interfacial bonding is formed at the interface and that Si-Si and Si-C are induced due to the hybridization of C-2p and Si-3p. Moreover, the Si-C is much stronger than Si-Si at the interface, implying that the contribution of the interfacial bonding mainly comes from Si-C rather than Si-Si.展开更多
First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-terminat...First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-termination is the preferred termination of the 6H-SiC（0001） polar surface and is more stable than the C-terminated 61-1- SiC（0001） polar surface over a wide range of allowed chemical potentials. Four stable atomic configurations （top, bridge, hcp and fcc） are considered, and the adsorption energies and geometries, Mulliken charge population, and partial density of state （PDOS） properties are analyzed. Adsorption energy results show that the top site is the most stable site. The structural properties of Si adsorption on the SiC （0001） surface shows that increasing stability means decreasing bond lengths. Charge populations analysis and PDOS results imply that there is strong interaction between Si adatoms and 6H-SiC （0001） surface.展开更多
文摘通过商用半导体模拟器MEDICI对700 V 4H-SiC晶闸管开通特性进行了模拟研究。模拟结果表明阳极电压小于100 V时,开通过程符合扩散模型,电压更高时,开通时间随阳极电压升高而迅速下降,符合场开通机制。不同于Si及GaAs晶闸管,SiC晶闸管p型耐压层中浅能级杂质Al使得其开通时间随温度的升高而降低。较厚的基区使得电导调制效应只发生在发射区与基区边界一个范围之内,随着温度的升高,其余部分的载流子数目指数增加,压降指数减小。开通时间随着门极触发电流的加大而逐渐缩短,减小到一定程度时,减小速度明显变缓。
文摘本文基于SMIC 28 nm CMOS工艺设计了一款应用于超宽带协议的具有带外噪声抑制功能的全集成低噪声放大器(Low Noise Amplifier,LNA),并提出了一种新型的LC串并联两级滤波结构.通过利用滤波器极点补偿LNA带内增益的设计方法,合理设计滤波负载等效电路的极点,使其略高于零点频率,在保证了LNA通带增益和噪声的情况下提高了滤波深度.对所设计的LNA进行了EMX建模及仿真验证.结果表明,该LNA在6.5~10 GHz的工作频带内,S_(21)高达21.17~25.28 d B,S_(11)小于-10.58 d B;S_(22)小于-11.20 d B,带内噪声系数仅为2.14~2.51 d B;带阻滤波器在5.8 GHz处可提供-35.45 d B的噪声抑制;在0.9 V供电电压下,LNA的静态功耗仅为9.36 m W.
基金Project supported by the National Natural Science Foundation of China （Grant No 60376011） and the Specialized Research Fund for the Doctoral Program of High Education, China （Grant No 20040700001）.
文摘SiCGe ternary alloys have been grown on SiC by hot-wall low-pressure chemical vapour deposition. It has been found that the samples cxhibit an island configuration, and the island growth of SiCGe epilayer depends on the processing parameters such as the growth temperature. When the growth temperature is comparatively low, the epilayer has two types of islands： onc is spherical island; another is cascading triangular island. With the increase of the growth temperature, the islands change from spherical to cascading triangular mode. The size and density of the islands depend on the growth duration and GeH4 flow-rate. A longer growth time and a larger GeH4 flow-rate can increase the size and density of the island in thc initial stage of the epitaxy. In our case, The optimal growth for a high density of uniform islands occurred at a growth temperature of 1100℃ for l-minute growth, with 10 SCCM GeH4, resulting in a narrow size distribution （about 30nm diameter） and high density （about 3.5 ×10^10 dots/cm2）. The growth follows Stranski- Krastanov modc （2D to 3D modc）, both of the islands and the 2D growth layer have face-centred cubic structure, and the critical thickness of the 2D growth layer is only 2.5 nm.
基金Project supported by the National Natural Science Foundation of China (Grant No 60576044)
文摘The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play the role of an light absorbing layer. This paper reports on Si films heteroepitaxially grown on the Si face of （0001） n-type 6H-SiC substrates and the use of B2H6 as a dopant for p-Si grown at temperatures in a range of 700-950℃. X-ray diffraction （XRD） analysis and transmission electron microscopy （TEM） tests have demonstrated that the samples prepared at the temperatures ranged from 850℃ to 900℃ are characterized as monocrystalline silicon. The rocking XRD curves show a well symmetry with FWHM of 0.4339° Omega. Twin crystals and stacking faults observed in the epitaxial layers might be responsible for widening of the rocking curves. Dependence of the crystal structure and surface topography on growth temperature is discussed based on the experimental results. The energy band structure and rectifying characteristics of the Si/SiC heterojunctions are also preliminarily tested.
基金Supported by the National Natural Science Foundation of China under Grant No 51177134the Natural Science Basic Research Plan in Shaanxi Province under Grant No 2012JQ8009+2 种基金Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant Nos 12JK0546 and 12JK0975China Postdoctoral Science Foundation under Grant No 2013M532072Doctoral Scientific Research Foundation of Xi’an Polytechnic University under Grant No BS1129.
文摘The energy-band structure and non-ultraviolet photoelectric properties of a Ni/n-Si/N^(+)-SiC isotype heterostruc-ture Schottky photodiode are simulated by using Silvaco-Atlas.There are energy offsets in the conduction and valance band of the heterojunction,which are about 0.09eV and 1.79eV,respectively.The non-UV photodiode with this structure is fabricated on a 6H-SiC(0001)substrate.𝐾J–V𝑊measurements indicate that the device has good rectifying behavior with a rectification ratio up to 200 at 5V,and the turn-on voltage is about 0.7V.Under non-ultraviolet illumination of 0.6W/cm^(2),the device demonstrates a significant photoelectric response with a photocurrent density of 2.9mA/cm^(2)and an open-circuit voltage of 63.0mV.Non-ultraviolet operation of the SiC-based photoelectric device is initially realized.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61076011 and 51177134)
文摘6H-SiC （1010） surface and Si （220）/6H-SIC （1010） interface with different stacking sites are investigated using first-principles calculations. Surface energies of 6H-SiC （1010） （case I, case II, and case III） are firstly studied and the surface calculation results show that case II and case III are more stable than case I. Then, the adhesion energies, fracture toughness values, interfacial energies, densities of states, and electronic structures of Si （220）/6H-SIC （1010） interfaces for three stacking models （AM, BM, and CM） are calculated. The CM model has the highest adhesion energy and the lowest interracial energy, suggesting that the CM is stronger and more thermodynamically stable than AM and BM. Densities of states and the total charge densities give evidence that interfacial bonding is formed at the interface and that Si-Si and Si-C are induced due to the hybridization of C-2p and Si-3p. Moreover, the Si-C is much stronger than Si-Si at the interface, implying that the contribution of the interfacial bonding mainly comes from Si-C rather than Si-Si.
基金Supported by the National Natural Science Foundation of China under Grant No 51177134
文摘First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-termination is the preferred termination of the 6H-SiC（0001） polar surface and is more stable than the C-terminated 61-1- SiC（0001） polar surface over a wide range of allowed chemical potentials. Four stable atomic configurations （top, bridge, hcp and fcc） are considered, and the adsorption energies and geometries, Mulliken charge population, and partial density of state （PDOS） properties are analyzed. Adsorption energy results show that the top site is the most stable site. The structural properties of Si adsorption on the SiC （0001） surface shows that increasing stability means decreasing bond lengths. Charge populations analysis and PDOS results imply that there is strong interaction between Si adatoms and 6H-SiC （0001） surface.
