α—PbO2型TiO2纳米晶微结构的HREM研究

TiO2是一种具有广泛应用前景的氧化物材料,其结构及相关的物理化学特性一直是实验和理论研究的焦点.常温常压下TiO2可以以四种形态存在,即锐钛矿、金红石、板钛矿和α-PbO2型.其中属四方晶系的金红石是最稳定的,其它几种形态在高温下都将转变成金红石.板钛矿和α-PbO2型TiO2都属正交晶系,但前者只是以亚稳相的形式存在,而后者则是一种高压淬火相.α-PbO2型TiO2可以在0.8到10.0GPa的压强下形成,其晶格参数为a=4.55、b=5.46、c=4.92[1].     

纳米晶SnO2气敏薄膜的制备与表征

以Ｓｎ（ＯＨ）４水合胶体为原料,采用溶胶－凝胶方法在Ｓｉ片上制备了ＳｎＯ２纳米晶薄膜,利用差热、热重、Ｘ光衍射以及原子力显微镜对薄膜的合成以及特性进行了分析,结果表明：在６００℃条件下烧结结晶的纳米晶薄膜表面平整,具有金红石结构,平均粒度在１０ｎｍ左右。以该薄膜为敏感体采用平面工艺制成的ＦＥＴ式气敏元件在常温下对乙醇蒸汽具有非常好的选择性。     

纳米晶SnO2气敏薄膜的制备与表征

以Sn(OH)4水合胶体为原料,采用溶胶-凝胶方法在Si片上制备了SnO2纳米晶薄膜,利用差热、热重、X光衍射以及原子力显微镜对薄膜的合成以及特性进行了分析,结果表明:在600°C条件下烧结结晶的纳米晶薄膜表面平整,具有金红石结构,平均粒度在10nm左右.以该薄膜为敏感体采用平面工艺制成的FET式气敏元件在常温下对乙醇蒸汽具有非常好的选择性.     

纳米GaN的制备及HREM观测

纳米ＧａＮ的制备及ＨＲＥＭ观测张庶元谢毅钱逸泰张裕恒（中国科技大学结构分析开放研究实验室，合肥２３００２６）ＧａＮ是一种宽能隙的半导体材料，具有制备光电器件的潜在应用价值［１，２］，因而受到日益增长的关注。据文献报道［３］，ＧａＮ具有三种物相，即纤锌...     

纳米晶SnO2薄膜的结晶特性

采用磁控溅射技术，使用混合气体Ar和O2，在衬底温度为150-400℃的耐热玻璃基片上制备了纳米晶SnO2：Sb透明导电薄膜，通过测定X射线衍射谱，表明薄膜择优取向为[110]和[211]方向，测量了SnO2：Sb薄膜的结晶特性随衬底温度变化以及纳米晶SnO2薄膜FE—SEM表面及断面形貌。     

纳米晶SnO2薄膜的结晶特性

采用磁控溅射技术,使用混合气体Ar和O2,在衬底温度为150～400℃的耐热玻璃基片上制备了纳米晶SnO2∶Sb透明导电薄膜,通过测定X射线衍射谱,表明薄膜择优取向为[110]和[211]方向.测量了SnO2∶Sb薄膜的结晶特性随衬底温度变化以及纳米晶SnO2薄膜FE-SEM表面及断面形貌.     

纳米晶SnO2薄膜的结晶特性

采用磁控溅射技术,使用混合气体Ar和O2,在衬底温度为150～400℃的耐热玻璃基片上制备了纳米晶SnO2∶Sb透明导电薄膜,通过测定X射线衍射谱,表明薄膜择优取向为[110]和[211]方向.测量了SnO2∶Sb薄膜的结晶特性随衬底温度变化以及纳米晶SnO2薄膜FE-SEM表面及断面形貌.     

热氧化法制备ZnO纳米针的微结构与场发射性质研究

ZnO是一种重要的宽禁带半导体材料，室温下带隙宽3.37eV，激子结合能高达60meV，在短波激光器、太阳能电池、压电材料、发光照明材料等方面具有广泛的应用前景。一维ZnO纳米材料具有高的长径比、良好的物理化学等性能，其合成备受关注。     

半导体陶瓷中孪晶的HREM和TEM研究

Oppolpzer曾用TEM这观察到BaTiO_3半导体陶瓷的孪晶,认为它会伴生异常晶粒长大。但是有关孪晶和孪晶界的结构细节以及形成机制尚不清楚。本文用高分辩电镜(HREM)和透射电镜(TEM)进一步研究了它们的孪晶,得到如下四点结果。1.BaTiO_3的大部分孪晶均为{111)孪晶,其晶界为共格倾斜(70°)孪晶界。图1是[110]方向孪晶的晶格像,图中用粗黑线示意镜面对称的(001)晶格(3.9A),与之垂直的为(110)晶格(2.8A),它相应于左右(指标化示意)上角的衍射结     

外加电场影响SnO2纳米晶簇光吸收

实验测量外加电场对 Ｓｎ Ｏ２ 纳米晶簇室温近紫外光吸收的影响程度，得到光吸收变化谱线和光吸收大小变化随外加电场变化曲线。它们均为一种非线性变化规律，在高电场区，光吸收变化值趋于饱和     

A silicon carbide LOCOS process using enhanced thermal oxidation by argon implantation

A process is described for creating local oxidation of silicon structure (LOCOS) structures in silicon carbide using enhanced thermal oxidation by argon implantation. Thicker oxides were created in selective regions by using multiple energy argon implants at a dose of 1 × 10¹⁵ cm⁻² prior to thermal oxidation. Atomic force microscopy was used to analyze the fabricated LOCOS structure.     

Radiation-enhanced thermal oxidation of silicon

A technique of radiation-enhanced thermal oxidation of silicon is developed and implemented in process equipment. Test SiO₂ films are grown under exposure to 511-keV gamma-ray photons. Their electrical and radiation performance are evaluated. Basic mechanisms of radiation-enhanced oxide growth are proposed.     

Wet thermal oxidation of GaN

Thermal oxidation of GaN was conducted at 700–900°C with O₂, N₂, and Ar as carrier gases for 525–630 Torr of H₂O vapor. Upon oxidation of both GaN powders and n-GaN epilayers, the monoclinic β-Ga₂O₃ phase was identified using glancing angle x-ray diffraction. The chemical composition of the oxide was verified using x-ray photoelectron spectroscopy. In experiments conducted using GaN powder, the oxide grew most rapidly when O₂ was the carrier gas for H₂O. The same result was obtained on n-type GaN epilayers. Furthermore, the thickness of the oxide grown in H₂O with O₂ as the carrier gas was found to be proportional to the oxidation time at all temperatures studied, and an activation energy of 210±10 kJ/mol was obtained. Scanning electron microscopy revealed a smoother surface after wet oxidation than was reported previously for dry oxidation. However, cross-sectional transmission electron microscopy revealed that the wet oxide/GaN interface was irregular and non-ideal for devicefabrication, even more so than the dry oxide/GaN interface. This observation was consistent with poor electrical properties.     

天然硫化橡胶热氧老化中太赫兹介电谱

天然橡胶制品的老化是其使用中普遍存在的现象,老化的本质是材料本身存在缺陷而容易被外部因素影响。介电谱是表征电介质对电磁波频率或温度的依赖关系,是微观极化的一种宏观体现。参照橡胶热空气老化标准GB/T3512-2014,对天然硫化橡胶在100℃实验箱中进行了1 000余小时热氧实验,研究样品的太赫兹介电谱随老化时间的变化关系。通过跟踪测试,获取了橡胶每24 h在0.2~1.2 THz的复介电常数和损耗角正切值有效数据,根据复介电常数数值可以推导橡胶的极化特点和统计性的微观运动类型,进而分析用太赫兹介电谱表征的天然硫化胶热氧老化过程中分子结构变化和相互的对应关系。由于材料老化的相通性,该结果对研究其他高分子材料的老化也能起到积极的意义。     

Ni and Ti silicide oxidation for CMOS applications investigated by XRD,XPS and FPP

Although silicide oxidation was studied 20 years ago, the interest of obtaining a robust process for new application appears significant today. Indeed, for the new architectural development process are required dense and narrow spaces. This paper focuses to bury a silicide layer under a protective layer such as silica in order to keep constant the physical and electrical properties of silicide after oxidation. Earlier works show the possibility to oxidize preferably the silicon (Si) in metal contained silicide rather than a pure crystalline Si at high temperatures. Thus, we first tried to reproduce and study these conditions and once acquired, targeted to decrease the oxidation temperature in order to fit with industrial requirements. Titanium (Ti) and Nickel (Ni) are chosen for their metallurgical interest and their integration capability in devices. Thus, four different group/phases (TiSi, TiSi₂, Ni₂Si, NiSi) of silicide were targeted by adjusting the temperature. In situ X-ray diffraction (XRD), photoelectron spectroscopy and sheet resistance (four point probe) measurements were carried out simultaneously before and after oxidation of silicide to characterize the phase and chemical composition. After silicide formation last three phases (TiSi₂, Ni₂Si, NiSi) were confirmed by XRD and G1(Ti/Si) was unknown, where only for NiSi was observed the low sheet resistance (≈7.3 Ω/□) and resistivity (18 μΩ·cm). After (dry, wet and plasma) oxidation, the phases of TiSi₂ and Ni₂Si changed and only NiSi was observed the constant phase, even pure SiO₂ was noted on NiSi after wet oxidation.     

InSb MOS structures fabricated by a novel thermal oxidation method

Interfaces between InSb and its native oxide grown by a novel thermal oxidation method have been clarified to have good electrical characteristics. The interface state density was of a V-shaped form with the minimum value of less than 1012/cm2 eV, and the field-effect mobility of the holes at 77 K was about 300 cm2/Vs.     

Models of boron redistribution during thermal oxidation withgeneral oxidation rate

It has been shown that the redistribution of boron in SiO₂ is negligible in the practical temperature range between 900 and 1100°C. Utilizing this fact, we derived a model for boron redistribution with a general oxidation rate, and obtained close agreement between experimental and theoretical data     

MOS structure fabrication by thermal oxidation of multilayer metal thin films

A novel approach for the fabrication of a metal oxide semiconductor(MOS) structure was reported.The process comprises electrochemical deposition of aluminum and zinc layers on a base of nickel-chromium alloy. This two-layer structure was thermally oxidized at 400℃for 40 min to produce thin layers of aluminum oxide as an insulator and zinc oxide as a semiconductor on a metallic substrate.Using deposition parameters,device dimensions and SEM micrographs of the layers,the device parameters were calculated.The resultant MOS structure was characterized by a C-V curve method.From this curve,the device maximum capacitance and threshold voltage were estimated to be about 0.74 nF and -2.9 V,respectively,which are in the order of model-based calculations.     

MOS structure fabrication by thermal oxidation of multilayer metal thin films

A novel approach for the fabrication of a metal oxide semiconductor(MOS) structure was reported.The process comprises electrochemical deposition of aluminum and zinc layers on a base of nickel-chromium alloy. This two-layer structure was thermally oxidized at 400℃for 40 min to produce thin layers of aluminum oxide as an insulator and zinc oxide as a semiconductor on a metallic substrate.Using deposition parameters,device dimensions and SEM micrographs of the layers,the device parameters were calculated.T...     

4H-SiC表面热氧化生长SiOx薄膜特性的研究

采用扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线光电子能谱（XPS）测试方法对4H-SiC上热氧化生长的氧化硅（SiOx）薄膜表面形貌进行观测,并分析研究SiOx薄膜和SiOx/4H-SiC界面的相关性质,包括拟合Si2p、O1s和C1s的XPS谱线和分析其相应的结合能,以及分析SiOx层中各主要元素随不同深度的组分变化情况,从而获得该热氧化SiOx薄膜的化学组成和化学态结构,并更好地了解其构成情况以及SiOx/4H-SiC的界面性质。