Al-H共掺杂ZnO薄膜的形貌及光致发光性能研究

在不同衬底温度条件下采用RF磁控溅射法在石英玻璃上沉积Al-H共掺杂ZnO薄膜.对所有样品进行晶体结构、表面形貌、电学、光学以及室温光致发光性能分析.结果表明:随着衬底温度的升高,ZnO薄膜的结晶度增加,晶粒增大,薄膜致密度增加;薄膜表面起伏变化减小;同时,电阻率最低达到7.58×10-4Ω·cm,透过率保持在75;左右.所有ZnO薄膜样品都以本征发光为主,Al-H共掺杂在一定程度降低ZnO薄膜缺陷发光的强度;随着衬底温度的升高,ZnO薄膜的本征发光强度明显增大;同时在能量为3.45 eV附近观察到了一个紫外发光峰.     

镓掺杂氧化锌透明导电薄膜的制备及其性能研究

采用射频磁控溅射方法在玻璃基片上制备了镓掺杂氧化锌(Ga∶ ZnO)透明导电薄膜,通过XRD、XPS、四探针仪和分光光度计等表征技术,研究了衬底温度对Ga∶ ZnO薄膜结构、组分、光学和电学性质的影响.结果表明:所有样品均为具有(002)择优取向的高质量透明导电薄膜,其晶体结构和光电性能与衬底温度密切相关.当衬底温度为673 K时,所制备的Ga∶ ZnO薄膜具有最大的晶粒尺寸(72.6 nm)、最低的电阻率(1.3×10-3Ω·cm)、较高的可见∶ZnO薄膜的光学能隙,结果显示随着衬底温度的升高,薄膜的光学能隙单调增加.     

衬底温度对直流反应磁控溅射法制备的N掺杂p型ZnO薄膜性能的影响

利用直流反应磁控溅射法(纯金属锌作为靶材,Ar-N2-O2混合气体作为溅射气体)在石英玻璃衬底上制备了N掺杂p型ZnO薄膜.通过XRD、Hall和紫外可见透射谱分别研究了衬底温度对ZnO薄膜结构性能、电学性能和光学性能的影响.XRD结果显示所有制备的薄膜都具有垂直于衬底的c轴择优取向,并且随着衬底温度的增加,薄膜的晶体质量得到了提高.Hall测试表明衬底温度对p型ZnO薄膜的电阻率具有较大影响,400℃下生长的p型ZnO薄膜由于具有较高的迁移率(1.32 cm2/Vs)和载流子浓度(5.58×1017cm-3),因此表现出了最小的电阻率(8.44Ω·cm).     

衬底温度对直流磁控溅射法制备掺锆氧化锌透明导电薄膜性能的影响

利用直流磁控溅射法在石英衬底上制备出了高透明导电的掺锆氧化锌(ZnO:Zr)薄膜.研究了衬底温度对ZnO:Zr薄膜结构、形貌及光电性能的影响.XRD表明实验中制备的ZnO:Zr为六方纤锌矿结构的多晶薄膜,具有垂直于衬底方向的c轴择优取向.实验所制备ZnO:Zr薄膜的晶化程度和导电性能对衬底温度有很强的依赖性.当衬底温度为300 ℃时, ZnO:Zr薄膜具有最小电阻率7.58×10-4 Ω·cm,其可见光平均透过率超过了91;.     

溅射气压对硼掺杂ZnO薄膜光电特性的影响

采用脉冲磁控溅射系统在玻璃衬底上制备了ZnO∶B薄膜,利用霍尔测试仪和紫外-可见光-近红外分光光度计及逐点无约束最优化法,研究了溅射气压(0.1 ～3 Pa)对ZnO薄膜的光学和电学特性的影响.结果表明:ZnO∶B薄膜在可见光区域内的平均透光率高于80;,近红外波段的透过率及薄膜的电阻率与溅射气压成正比;折射率n随溅射气压降低呈下降趋势,其值介于1.92 ～2.09之间;在较低的溅射气压下(PAr=0.1 Pa)获得的薄膜电阻率最小(3.7×10-3Ω·cm),且对应着小的光学带隙(Eg=3.463 eV).     

衬底温度对MOCVD-ZnO薄膜特性的影响

利用金属有机物化学气相沉积(MOCVD)生长技术,制备本征ZnO薄膜,并研究薄膜的结构、形貌及光电等性能.结果表明:衬底温度对ZnO薄膜的微观结构、电学、光学及表面形貌等有显著影响.在衬底温度为180℃时获得电阻率为2.17×10-2Ω·cm.平均透过率为85;的低电阻、高透过率、结晶质量高、表面呈绒面结构的本征ZnO薄膜.对本征ZnO薄膜进一步掺杂和结构优化有望用于硅薄膜太阳能电池的前电极.     

衬底温度对Al掺杂ZnO薄膜结构及其光电性能的影响

利用溅射方法制备了Al掺杂ZnO(AZO)薄膜,探究了衬底温度对薄膜的形貌特征、结构和光电性能的调控.实验结果表明:衬底温度可以调控AZO薄膜的生长方式以及光电性能.随着衬底温度的升高,AZO薄膜从无规则的形状转变为球形并且其颗粒尺寸逐渐减小.XRD分析表明样品的结晶质量随着衬底温度的升高而变佳.透射光谱研究发现,在低衬底温度下,400 nm附近处有一吸收台阶,随着衬底温度升高,此吸收台阶消失,表明衬底温度影响着AZO内部的缺陷.电学性质研究表明随着衬底温度升高,AZO薄膜的导电性能也随着升高,电阻率从9×10-2 Ω·cm降到5×10-3 Q·cm.而其载流子浓度从6×1019 cm-3增加到2.2×1020 cm-3.     

缓冲层对溶胶凝胶制备ZnO∶ Sn薄膜性能的影响

采用溶胶凝胶旋涂法,在石英衬底上引入缓冲层制备ZnO∶Sn薄膜.利用四探针电阻率测试仪、X射线衍射仪(XRD)、光致发光(PL)谱仪、场发射扫描电子显微镜(FE-SEM)等测试手段对薄膜的微观结构和光电性能进行表征.结果表明:所制样品均呈现六角纤锌矿晶体结构并沿C轴择优生长,薄膜的结晶质量和光电性能达到改善,适当厚度的缓冲层可以有效缓解薄膜和衬底间的晶格失配.随着缓冲层厚度的增加,薄膜的电导率以及在可见光范围的透过率先增大后减小.制备两层缓冲层薄膜性能最优,电阻率达到9.5×10-3 Ω·cm,可见光波段的平均透过率为91;.     

Nb掺杂ZnO透明导电薄膜的结构以及光电性能研究

采用直流磁控溅射法在玻璃衬底上制备了高质量的Nb掺杂ZnO( NZO)透明导电薄膜.为了研究薄膜厚度对薄膜性质的影响,制备了五个厚度分别为239 nm,355 nm,489 nm,575 nm和679 nm的样品.XRD结果表明,ZnO∶ Nb薄膜是具有六角纤锌矿结构的多晶薄膜,并且具有垂直于衬底的c轴择优取向.随着膜厚的增加,薄膜的结晶质量明显提高.当厚度从239 nm增加到489 nm时,平均晶粒尺寸从19.7 nm增加到24.7 nm,薄膜的电阻率持续减小;当厚度进一步增加时,晶粒尺寸略有减小,电阻率有所增加.本实验获得的最低电阻率为4.896×10-4Ω·cm.随膜厚的增加,光学带隙先增大后减小.所有薄膜在可见光区域的平均透过率均超过88.3;.     

退火温度对Li:ZnO薄膜紫外发射性能影响

利用溶胶-凝胶法在Si衬底上制备不同退火温度的Li∶ZnO薄膜。借助X射线衍射(XRD)、X射线光电子谱(XPS)、扫描电镜(SEM)和光致发光(PL)谱研究样品结晶质量、成分、表面形貌和发光特性。结果表明:所有样品均高度c轴择优取向生长;随退火温度升高,样品结晶性变好,紫外发射增强。LiOH在退火温度超过700℃分解,使Li、H进入到ZnO晶格,在ZnO薄膜中形成LiZn-H复合缺陷,这种复合缺陷使H被困在ZnO薄膜中,形成H施主,显著提高ZnO薄膜紫外发光强度,抑制ZnO薄膜绿光发射。     

Relationship of Morphological Types of Dynamic Forms of Crystals

Crystallography Reports - The relationship of morphological spectra (sets of data on the morphological types of real polyhedral crystals and their probabilities under current physicochemical...     

Development of Pauling's concepts of geometric characteristics of atoms

The evolution of the geometric characteristics introduced by Pauling and their dependence on the specific features of the structure and chemical bonds have been considered. The values of the covalent and van der Waals radii are given as well as their relationships and mutual transitions.     

A review of measurement of thermophysical properties of silicon melt

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi₃ existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.     

Generation of crystal structures of heteromolecular compounds by the method of discrete modeling of packings

Within the method of discrete modeling of packings, an algorithm of generation of possible crystal structures of heteromolecular compounds containing two or three molecules in the primitive unit cell, one of which has an arbitrary shape and the other (two others) has a shape close to spherical, is proposed. On the basis of this algorithm, a software package for personal computers is developed. This package has been approved for a number of compounds, investigated previously by X-ray diffraction analysis. The results of generation of structures of five compounds—four organic salts (with one or two spherical anions) and one solvate—are represented.     

Investigation of the Mechanism of Influence of Stress Corrosion on the Development of Macroplastic Instabilities of Aluminum–Magnesium Alloy

Crystallography Reports - Macroscopic jumps of plastic deformation (few percent in amplitude) on creep curves of aluminum–magnesium alloy, caused by a local effect of concentrated solution of...     

Comparative analysis of two methods of calculation of the orientation of domain walls in ferroelastics

Two types of domain-wall equations are analyzed: the equations derived by the Sapriel method and the equations obtained by interface matching of the thermal-expansion tensor. It is shown that, for W-type domain walls, these methods yield the same equations. For W′-type domain walls, the equations obtained by different methods coincide for proper ferroelastics and differ for improper ferroelastics.     

Dependence of the parameters of equations of viscous flow on chemical composition of silicate melts

The temperature dependence of viscosity of silicate melts is discussed in the framework of the Avramov–Milchev (AM) equation. The composition is described by means of two parameters: the molar fraction, x, and the “lubricant fraction”, l. The molar fraction is the sum of the molar parts x_i of all oxides dissolved in SiO₂, the molar fraction of the latter being 1 ? x. It is shown that, with sufficient precision, two of the parameters of the AM equation can be presented as unique functions of the molar fraction. On the other hand, x is not sufficient to determine properly the reference temperature T_r , at which viscosity is η_r = 10¹³ [dPa.s]. Therefore, additional parameter, “lubricant fraction” l, is introduced. For each of the components, l_i is a product of molar part x_i and a specific dimensionless coefficient 0 ≤ k_i ≤ 1 accounting for the specific contribution of this component to the increased mobility of the system. It is demonstrated that, for l > 0, the reference temperature is related to the “lubricant fraction” l through the reference temperature T_r,SiO2 of pure SiO₂.     

A SAXS study of kinetics of aggregation of silica sols

SAXS in situ experiments on the evolution of TMOS solutions during hydrolysis and polycondensation lead to power laws with scaling exponents ≈ 2. It is suggested that this could be the result of the polydispersity of the samples and that only an apparent fractal dimension can be obtained in this way. Kinetic studies tend to indicate that agglomeration in the sol is the result of a diffusion-controlled process.     

Study of the possibility of interactive control of the surface profile of X-ray optical elements

We investigate the possibility of controlling the curvature parameters of parabolic mirrors that are modular elements of two types consisting of a base and thin inserts placed at the opposite side of the work surface. In the first type of modular elements, bending is controlled by the difference in the coefficients of the thermal expansion of the base and inserts. In the second type of elements, the profile is changed by the piezoelectric straining of the inserts under an electric field. A correlation is established between the parameters of modular elements and their surface curvature profile.