采用数值模拟研究PVT法φ150 mm 4H-SiC单晶生长的功率、频率选择、坩埚位置及保温厚度等关键生长参数。研究表明φ150 mm 4H-SiC单晶生长功率是2inch 4H-SiC生长功率的2倍,优化的加热频率在5 k Hz以下,系统分析不同生长参数下生长腔内...采用数值模拟研究PVT法φ150 mm 4H-SiC单晶生长的功率、频率选择、坩埚位置及保温厚度等关键生长参数。研究表明φ150 mm 4H-SiC单晶生长功率是2inch 4H-SiC生长功率的2倍,优化的加热频率在5 k Hz以下,系统分析不同生长参数下生长腔内径向及轴向温度梯度的变化规律。在此基础上初步的进行了φ150 mm 4H-SiC单晶的生长工作,获得了无裂纹、直径完整的高质量SiC衬底材料。拉曼光谱Mapping测量显示φ150 mm SiC衬底全片无多型,均为4H-SiC晶型。X光摇摆曲线显示半宽小于30 arcsec。采用掺杂过渡金属V杂质,获得了电阻率超过5×109Ω·cm的150 mm SiC衬底。展开更多
The Puguang （普光） gas field is the largest gas field found in marine carbonates in China. The Feixianguan （飞仙关） and Changxing （长兴） reservoirs are two such reservoirs that had been buried to a depth of abou...The Puguang （普光） gas field is the largest gas field found in marine carbonates in China. The Feixianguan （飞仙关） and Changxing （长兴） reservoirs are two such reservoirs that had been buried to a depth of about 7 000 m and experienced maximum temperature of up to 220 ℃ before uplift to the present-day depth of 5 000-5 500 m, with present-day thermal maturity between 2.0% and 3.0% equivalent vitrinite reflectance （Ro）. Bitumen staining is ubiquitous throughout the Feixianguan and Changxing formations, with the greatest concentrations in zones with the highest porosity and permeability, suggesting that the solid bitumen is the result of in-situ cracking of oil. According to the distribution of bitumen in the core, the paleo-oil boundary can be approximately determined. The paleo-oil resource is calculated to be about （0.61-0.92） × 10^9 t （average 0.76 × 10^9 t）, and the cracked gas volume is about （380.80-595.80） × 10^9 m^3 （average 488.30 × 10^9 m^3）; at least 58.74% of cracked gas is preserved in Puguang gas field. The study area experienced not only the cracking of oil but also thermochemical sulfate reduction, resulting in large quantities of nonhydrocarbon gas, with about 15.2% H2S and 8.3% CO2, together with the structural reconfiguration. During the whole process, the great change of volume and pressure compels the PVTsim modeling software to simulate various factors, such as the cracking of oil, the thermochemical sulfate reduction （TSR） and the tectonic uplift in both isolated and open geological conditions, respectively. The results show that although any one of these factors may induce greater pressure changes in an isolated system than in a closed system, the oil cracking and C3＋ involving TSR lead to overpressure during the early stage of gas reservoir. Therefore, the tectonic uplift and the methane-dominated TSR, as well as the semi-open system contribute to the reducing pressure resulting in the current normal formation pressure.展开更多
文摘采用数值模拟研究PVT法φ150 mm 4H-SiC单晶生长的功率、频率选择、坩埚位置及保温厚度等关键生长参数。研究表明φ150 mm 4H-SiC单晶生长功率是2inch 4H-SiC生长功率的2倍,优化的加热频率在5 k Hz以下,系统分析不同生长参数下生长腔内径向及轴向温度梯度的变化规律。在此基础上初步的进行了φ150 mm 4H-SiC单晶的生长工作,获得了无裂纹、直径完整的高质量SiC衬底材料。拉曼光谱Mapping测量显示φ150 mm SiC衬底全片无多型,均为4H-SiC晶型。X光摇摆曲线显示半宽小于30 arcsec。采用掺杂过渡金属V杂质,获得了电阻率超过5×109Ω·cm的150 mm SiC衬底。
基金supported by the National Basic Research Program of China (No. 2005CB422105)the National Natural Science Foundation of China (No. 40772089)
文摘The Puguang （普光） gas field is the largest gas field found in marine carbonates in China. The Feixianguan （飞仙关） and Changxing （长兴） reservoirs are two such reservoirs that had been buried to a depth of about 7 000 m and experienced maximum temperature of up to 220 ℃ before uplift to the present-day depth of 5 000-5 500 m, with present-day thermal maturity between 2.0% and 3.0% equivalent vitrinite reflectance （Ro）. Bitumen staining is ubiquitous throughout the Feixianguan and Changxing formations, with the greatest concentrations in zones with the highest porosity and permeability, suggesting that the solid bitumen is the result of in-situ cracking of oil. According to the distribution of bitumen in the core, the paleo-oil boundary can be approximately determined. The paleo-oil resource is calculated to be about （0.61-0.92） × 10^9 t （average 0.76 × 10^9 t）, and the cracked gas volume is about （380.80-595.80） × 10^9 m^3 （average 488.30 × 10^9 m^3）; at least 58.74% of cracked gas is preserved in Puguang gas field. The study area experienced not only the cracking of oil but also thermochemical sulfate reduction, resulting in large quantities of nonhydrocarbon gas, with about 15.2% H2S and 8.3% CO2, together with the structural reconfiguration. During the whole process, the great change of volume and pressure compels the PVTsim modeling software to simulate various factors, such as the cracking of oil, the thermochemical sulfate reduction （TSR） and the tectonic uplift in both isolated and open geological conditions, respectively. The results show that although any one of these factors may induce greater pressure changes in an isolated system than in a closed system, the oil cracking and C3＋ involving TSR lead to overpressure during the early stage of gas reservoir. Therefore, the tectonic uplift and the methane-dominated TSR, as well as the semi-open system contribute to the reducing pressure resulting in the current normal formation pressure.
