二氧化硅薄膜至今依然属人们广泛研究的材料,这是因为当这种材料制备为高质量的超薄、极薄的氧化物时,可实际应用于不同方面,如超大规模集成电路(VLSI)的栅氧化层以及液晶显示屏(LCD)的生产。本文考察了厚度为3nm和5nm的极薄二氧化硅层...二氧化硅薄膜至今依然属人们广泛研究的材料,这是因为当这种材料制备为高质量的超薄、极薄的氧化物时,可实际应用于不同方面,如超大规模集成电路(VLSI)的栅氧化层以及液晶显示屏(LCD)的生产。本文考察了厚度为3nm和5nm的极薄二氧化硅层的结构性质,这些薄层是通过适度掺杂n-型硅(100)晶片而形成。在形成氧化层之前用标准RCA方法清洁,并随后在氮气氛围中退火,部分样品在HCN溶液中钝化。本研究中用傅立叶变换红外光谱(FT-IR)技术获取了复合结构中不同类型的化学键信息。对SiO2钝化试样和非钝化试样中的Si-O-Si的不对称伸缩振动分别用纵光(LO)和横光(TO)模式进行了鉴别,发现TO模式位置(约1 107cm-1)和振幅与试样的厚度无关。另一方面,LO模式的位置从约1 230cm-1(厚度约为1.5nm)改变为1 244cm-1左右(厚度约为4.5nm)。根据红外光谱峰的偏移,认为超薄和极薄SiOx复合结构并不均匀。对红外光谱获得的结果进行了反褶积处理并获取相关信息。用次级离子质谱分析法(SIMS,Secondary Ion Mass Spectrometry)考察了试样的原子组成,发现NH键的数量也与技术条件相关。基于记录的试样X-反射率数据的理论处理结果,用原始方法确定了材料的结构性质、层密度、表面粗糙度以及相应界面,并将所得结果与原子力显微镜所获得的结果进行了对比和讨论。借助于深能阶瞬态光谱学中的电荷变形,证实HCN溶液对二氧化硅/硅界面密度的强钝化影响。钝化后,发现新形成的界面深处缺陷阱其密度可以忽略不计,这是因为其形成原因与钝化过程中在界面处引入的NH原子对存在相关。展开更多
Mesoporous Technische Universiteit Delft（TUD-1）-supported chromium oxide-doped titania（Cr-TiO2） was developed as a promising photocatalyst for phenol photodegradation under visible light irradiation.Low-angle X-ra...Mesoporous Technische Universiteit Delft（TUD-1）-supported chromium oxide-doped titania（Cr-TiO2） was developed as a promising photocatalyst for phenol photodegradation under visible light irradiation.Low-angle X-ray diffraction and Fourier transform infrared spectroscopy results confirmed the amorphous and mesoporous silicate framework of TUD-1 in TUD-1-supported Cr-TiO2.The mesostructure of TUD-1 was further verified via N2 adsorption-desorption analysis,which showed a type-IV isotherm with a narrow average pore size distribution of 3.9 nm and high surface area of 490 m^2/g.Transmission electron microscopy analysis results indicated that TUD-1-supported Cr-TiO2 contained nanoparticles and porous channels.An increase in band gap energy was observed after loading Cr-TiO2 into TUD-1.Compared with that of unsupported Cr-TiO2,TUD-1-supported Cr-TiO2 showed higher photocatalytic activity for phenol degradation under visible light irradiation.The TUD-1 supported Cr-TiO2 photocatalyst with a Si/Ti molar ratio of 30 exhibited the highest photodegradation of phenol（82%） of the prepared samples.The photodegradation of phenol by the supported catalyst followed the Langmuir adsorption isotherm with first-order kinetics.展开更多
文摘二氧化硅薄膜至今依然属人们广泛研究的材料,这是因为当这种材料制备为高质量的超薄、极薄的氧化物时,可实际应用于不同方面,如超大规模集成电路(VLSI)的栅氧化层以及液晶显示屏(LCD)的生产。本文考察了厚度为3nm和5nm的极薄二氧化硅层的结构性质,这些薄层是通过适度掺杂n-型硅(100)晶片而形成。在形成氧化层之前用标准RCA方法清洁,并随后在氮气氛围中退火,部分样品在HCN溶液中钝化。本研究中用傅立叶变换红外光谱(FT-IR)技术获取了复合结构中不同类型的化学键信息。对SiO2钝化试样和非钝化试样中的Si-O-Si的不对称伸缩振动分别用纵光(LO)和横光(TO)模式进行了鉴别,发现TO模式位置(约1 107cm-1)和振幅与试样的厚度无关。另一方面,LO模式的位置从约1 230cm-1(厚度约为1.5nm)改变为1 244cm-1左右(厚度约为4.5nm)。根据红外光谱峰的偏移,认为超薄和极薄SiOx复合结构并不均匀。对红外光谱获得的结果进行了反褶积处理并获取相关信息。用次级离子质谱分析法(SIMS,Secondary Ion Mass Spectrometry)考察了试样的原子组成,发现NH键的数量也与技术条件相关。基于记录的试样X-反射率数据的理论处理结果,用原始方法确定了材料的结构性质、层密度、表面粗糙度以及相应界面,并将所得结果与原子力显微镜所获得的结果进行了对比和讨论。借助于深能阶瞬态光谱学中的电荷变形,证实HCN溶液对二氧化硅/硅界面密度的强钝化影响。钝化后,发现新形成的界面深处缺陷阱其密度可以忽略不计,这是因为其形成原因与钝化过程中在界面处引入的NH原子对存在相关。
基金the Ministry of Higher Education,Malaysia and Universiti Teknologi Malaysia(UTM) for the financial supports through Research University Grants (Q.J130000.2426.03G35 and Q.J130000.2526.10H54)
文摘Mesoporous Technische Universiteit Delft（TUD-1）-supported chromium oxide-doped titania（Cr-TiO2） was developed as a promising photocatalyst for phenol photodegradation under visible light irradiation.Low-angle X-ray diffraction and Fourier transform infrared spectroscopy results confirmed the amorphous and mesoporous silicate framework of TUD-1 in TUD-1-supported Cr-TiO2.The mesostructure of TUD-1 was further verified via N2 adsorption-desorption analysis,which showed a type-IV isotherm with a narrow average pore size distribution of 3.9 nm and high surface area of 490 m^2/g.Transmission electron microscopy analysis results indicated that TUD-1-supported Cr-TiO2 contained nanoparticles and porous channels.An increase in band gap energy was observed after loading Cr-TiO2 into TUD-1.Compared with that of unsupported Cr-TiO2,TUD-1-supported Cr-TiO2 showed higher photocatalytic activity for phenol degradation under visible light irradiation.The TUD-1 supported Cr-TiO2 photocatalyst with a Si/Ti molar ratio of 30 exhibited the highest photodegradation of phenol（82%） of the prepared samples.The photodegradation of phenol by the supported catalyst followed the Langmuir adsorption isotherm with first-order kinetics.
