To alleviate catalytic coking on the inner surface of radiant tube for ethylene production in petrochemical plants,SiO2/S coatings were deposited on HP40 alloy specimens using dimethyldisulfide (DMDS) and tetraethox...To alleviate catalytic coking on the inner surface of radiant tube for ethylene production in petrochemical plants,SiO2/S coatings were deposited on HP40 alloy specimens using dimethyldisulfide (DMDS) and tetraethoxysilane (TEOS) by atmospheric pressure chemical vapor deposition (APCVD). A two-dimension mathematical model was made to predict the growth rate of SiO2/S coating and to study the effects of deposition parameters on the deposition rate. The results show that the predicted deposition rate is in good agreement with the experimental one. The deposition rate mainly depends on the concentrations of precursors in the total gas flow, concentrations of intermediates on the deposition surface, total gas flow rate and deposition temperature. The weight of SiO2/S coating linearly increases with the deposition time. When the gas flow rate is below 0.3 m/s, the rate-limiting step of SiO2/S coating deposition is the diffusions of intermediates.However, the surface reactions of intermediates will be the rate-limiting step after the gas flow rate is above 0.3 m/s. When the deposition temperature is below 780℃, the rate-limiting step of SiO2/S coating deposition mainly depends on the surface reactions of intermediates. When the deposition temperature is above 780℃,the rate-limiting step depends on the diffusions of intermediates. The deposition rate increases with increasing the concentrations of the intermediates. However, when the partial pressures of the intermediates reach 8 Pa,the deposition rate keeps constant.展开更多
Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2...Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16~400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 :F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.展开更多
在重掺硅衬底片背封过程中,硅片表面颗粒的尺寸和数量将会极大的影响到沉积薄膜的质量,并影响硅片几何特征的形成。主要针对不同掺杂剂的200 mm重掺衬底硅片在进行常压化学气相沉积(atmospheric-pressure chemical vapor deposition, AP...在重掺硅衬底片背封过程中,硅片表面颗粒的尺寸和数量将会极大的影响到沉积薄膜的质量,并影响硅片几何特征的形成。主要针对不同掺杂剂的200 mm重掺衬底硅片在进行常压化学气相沉积(atmospheric-pressure chemical vapor deposition, APCVD)生长SiO2薄膜前的颗粒沾污开展研究。将经过相同清洗及干燥工艺处理的硅片放置于有风机过滤机组(fan filter unit, FFU)存在的百级环境中,利用表面激光扫描方法对硅片表面粒径在0.3~0.5μm范围的颗粒进行测试,分析重掺衬底硅片表面颗粒随存放时间的增长情况。结果表明:在有FFU存在的百级环境中,随存放时间的延长:(1)同种掺杂剂硅片表面颗粒呈增长趋势,且粒径小的颗粒增长幅度较大;(2)不同掺杂剂硅片中,相比于重掺As, Sb的硅片,重掺B硅片表面颗粒的增长速度最快,而其他两种掺杂剂硅片表面颗粒增长速度相对较缓且差别不大。展开更多
摘要To alleviate catalytic coking on the inner surface of radiant tube for ethylene production in petrochemical plants,SiO2/S coatings were deposited on HP40 alloy specimens using dimethyldisulfide (DMDS) and tetraethoxysilane (TEOS) by atmospheric pressure chemical vapor deposition (APCVD). A two-dimension mathematical model was made to predict the growth rate of SiO2/S coating and to study the effects of deposition parameters on the deposition rate. The results show that the predicted deposition rate is in good agreement with the experimental one. The deposition rate mainly depends on the concentrations of precursors in the total gas flow, concentrations of intermediates on the deposition surface, total gas flow rate and deposition temperature. The weight of SiO2/S coating linearly increases with the deposition time. When the gas flow rate is below 0.3 m/s, the rate-limiting step of SiO2/S coating deposition is the diffusions of intermediates.However, the surface reactions of intermediates will be the rate-limiting step after the gas flow rate is above 0.3 m/s. When the deposition temperature is below 780℃, the rate-limiting step of SiO2/S coating deposition mainly depends on the surface reactions of intermediates. When the deposition temperature is above 780℃,the rate-limiting step depends on the diffusions of intermediates. The deposition rate increases with increasing the concentrations of the intermediates. However, when the partial pressures of the intermediates reach 8 Pa,the deposition rate keeps constant.
摘要Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16~400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 :F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.
摘要在重掺硅衬底片背封过程中,硅片表面颗粒的尺寸和数量将会极大的影响到沉积薄膜的质量,并影响硅片几何特征的形成。主要针对不同掺杂剂的200 mm重掺衬底硅片在进行常压化学气相沉积(atmospheric-pressure chemical vapor deposition, APCVD)生长SiO2薄膜前的颗粒沾污开展研究。将经过相同清洗及干燥工艺处理的硅片放置于有风机过滤机组(fan filter unit, FFU)存在的百级环境中,利用表面激光扫描方法对硅片表面粒径在0.3~0.5μm范围的颗粒进行测试,分析重掺衬底硅片表面颗粒随存放时间的增长情况。结果表明:在有FFU存在的百级环境中,随存放时间的延长:(1)同种掺杂剂硅片表面颗粒呈增长趋势,且粒径小的颗粒增长幅度较大;(2)不同掺杂剂硅片中,相比于重掺As, Sb的硅片,重掺B硅片表面颗粒的增长速度最快,而其他两种掺杂剂硅片表面颗粒增长速度相对较缓且差别不大。