MgxZn1-xO单晶薄膜的分子束外延生长及结构表征

用等离子辅助分子束外延(P-MBE)的方法,在蓝宝石c-平面上外延生长了MgxZn1-xO合金薄膜.在0≤x≤0.2范围内MgxZn1-xO薄膜保持着六角纤锌矿结构不变.原位反射式高能电子衍射图样和X射线双晶衍射谱的结果表明生长的样品是单晶薄膜.随着x值逐渐增大,Mg2+离子逐渐进入ZnO的晶格,X射线双晶衍射测得样品的(002)取向的半高宽度从0.249°增加到0.708°,表明结晶质量逐渐下降,(002)方向的X射线衍射峰向大角度方向移动,晶格常数c由5.205(A)减小到5.185(A).透射光谱的结果表明,合金薄膜的吸收边随着Mg离子的掺入逐渐向高能侧移动,室温光致发光谱出现很强的紫外发光(NBE)峰,没有观察到深能级(DL)发射,且随着Mg掺入量的增加,紫外发光峰有明显的蓝移,这与透射光谱的结果是相吻合的.     

利用Mg含量控制Zn_(1-x)Mg_xO薄膜压敏电阻器的阈值电压

利用溶胶-凝胶法制备了Zn1-xMgxO压敏薄膜,并通过X射线衍射、X射线能谱、紫外-可见光谱仪、I-V特性测试仪等对薄膜及其压敏特性进行了表征。XRD结果表明,掺Mg后Zn1-xMgxO薄膜仍然为六方纤锌矿ZnO晶体结构;紫外-可见吸收谱表明,随着薄膜中Mg含量的增加,薄膜的吸收边蓝移,禁带宽度增加。I-V特性曲线表明,基于Al/Zn1-xMgxO/Si结构的薄膜压敏电阻器的阈值电压随着Mg含量的增加而增加,因此可以通过调节Mg含量实现对Zn1-xMgxO薄膜压敏电阻器阈值电压的调节。上述现象表明,Zn1-xMgxO薄膜压敏电阻器的压敏阈值电压与禁带宽度有关,即与Zn1-xMgxO薄膜中电子的本征跃迁有关。     

硼碳氮薄膜的脉冲激光沉积及其光学性能

采用脉冲激光沉积技术,在Si(100)和石英基片上制备了硼碳氮薄膜(BCN)。利用X射线衍射(XRD),傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和紫外-可见分光光度计对BCN薄膜进行了表征,研究了激光能量密度对BCN薄膜沉积速率、组分、结构和光学性能的影响。FTIR和XPS分析结果表明BCN薄膜中包含B-C,C-N和N-B化学键,说明实现了B、C和N的原子级化合。当激光能量密度从1 J/cm2增加到6 J/cm2时,BCN薄膜的沉积速率加快,N含量由7.2%增加到15%,光学禁带宽度(Eg)从4.02 eV降低到3.82 eV,Eg的降低主要与BCN薄膜中碳含量的增加有关。     

复合钒钛酸干凝胶薄膜的制备及表征

以V2O5粉末和钛酸丁酯为原料,采用溶胶一凝胶法制备了复合钒钛酸干凝胶(H2V12-xTixO31-y·nH2O(0≤x≤8))薄膜,并时其进行了红外光谱、X射线光电子能谱、热重和X射线衍射分析.结果表明,随着Ti含量的增加,HzV12-xTixO31-y·nH2O中与V有关的振动吸收峰向低频方向移动,且强度减弱;干凝胶薄膜中V以+4价和+5价状态存在,Ti以+4价状态存在;复合钒钛酸干凝胶薄膜为层状结构,Ti取代部分V后改变了层间距,并且其变化是非单调的.     

不同晶粒尺寸Mg掺杂(Ba0.6Sr0.4)0.925K0.075TiO3薄膜的直流场介电性能研究

采用溶胶凝胶工艺,在Pt/Ti/SiO2/Si衬底制备了Mg掺杂(Ba0.6Sr0.4)0.925K0.075TiO3(BSKT)薄膜.X射线衍射(XRD)和扫描电镜(SEM)分析测定了物相微结构和薄膜表面形貌,研究了Mg掺杂含量对BSKT晶粒尺寸和直流场介电调谐性能的影响,讨论了直流场介电损耗谱演变的原因.结果表明,Mg掺杂BSKT使薄膜表面粗糙度、晶粒尺寸、介电常量、介电损耗和调谐量都降低;在室温1MHz下,BSKT薄膜有最大的调谐量73.6%;6%(摩尔分数)Mg掺杂BSKT薄膜有最低的介电损耗为0.0088;发现直流场下薄膜的介电损耗谱演变一方面可能与薄膜的晶粒尺寸有关,另一方面也可能与测试温度有关.     

磁控溅射MgxZn1-xO薄膜的结构与光学性能研究

利用射频磁控溅射技术在玻璃衬底上沉积了MgxZn1-xO(x=0～0.2)薄膜.采用X射线衍射仪、紫外-可见光分光光度计和荧光光谱仪研究了Mg掺杂量对MgxZn1-xO薄膜结构与光学性能的影响.XRD图谱表明,MgxZn1-xO薄膜均为六角纤锌矿结构,并且呈现出C轴择优生长特性,当x>0.1时薄膜出现(100)面衍射峰,薄膜的c轴择优生长特性减弱,随着x值的增加,晶格常数c逐渐减小.紫外可见光透射光谱表明,Mg的掺入提高了薄膜在可见光范围内的透过率,同时使薄膜的禁带宽度增大.PL谱分析显示,Mg的掺入使薄膜的紫外发射峰和蓝光发射带发生蓝移,当x=0.1时近带边发射峰与杂质发射的强度比值最高.     

溶胶-凝胶法制备Na/Mg共掺ZnO薄膜的特性研究

利用溶胶-凝胶旋涂法制备了Na/Mg共掺ZnO薄膜。通过与未掺杂及只掺Mg的ZnO薄膜的对比分析,重点研究了Na/Mg共掺ZnO薄膜的结构、光学及电学特性。扫描电子显微镜(SEM)图像、X射线衍射(XRD)图谱、透射光谱及PL谱的分析结果表明,Na/Mg共掺有利于提高ZnO薄膜的结晶特性及c轴择优取向性。Na/Mg共掺会使得ZnO薄膜的禁带宽度增加,但增加的幅度小于单独掺Mg引起的禁带宽度增加。消除氧空位缺陷后,Na/Mg共掺ZnO薄膜将是一种很好的紫外发光材料。霍尔效应分析结果表明,Na/Mg共掺杂可将ZnO薄膜导电性从N型转变为P型,且使电阻率有很大幅度的增加。     

Al-C-N非晶薄膜结构及导电性研究

为了揭示Al-C-N非晶薄膜的结构、导电性以及它们之间的关系,本文采用非平衡磁控溅射沉积技术在Si(100)基体上沉积得到了不同Al含量的Al-C-N薄膜。使用X射线光电子能谱仪、X射线衍射和高分辨透射电镜研究了所制备薄膜的相组成和微观结构。采用四引线法测定了薄膜电阻率-温度关系和霍尔电阻率-磁场关系。实验结果表明,所制备薄膜为非晶结构,结构致密,没有明显的缺陷,薄膜中主要的化学键为C-N,C-C和Al-N键。薄膜的成分对其导电性能有着明显的影响,当Al含量较低时,Al-C-N薄膜为p型半导体;当Al含量较高时薄膜转变为绝缘体。     

衬底温度对Mg0.1Zn0.9O薄膜结构及光学性能的影响

利用射频磁控溅射技术在不同温度的(100)Si和玻璃衬底上成功地制备了c轴择优取向的Mg0.1Zn0.9O薄膜.通过X射线衍射(XRD)、场发射扫描电镜(FESEM)、紫外可见光分光光度计和光致发光谱研究了衬底温度对Mg0.1Zn0.9O薄膜结构、表面形貌和光学性能的影响,结果表明,在衬底温度为400℃时生长的Mg0.1Zn0.9O薄膜具有很好的c轴取向和较好的光学性能.用激发波长为300nm的氙灯作为激发光源得到不同衬底温度下Mg0.1Zn0.9O薄膜的室温PL谱.分析表明,紫外发光峰与薄膜的结晶质量密切相关,蓝光发射与氧空位有关.简单探讨了衬底温度影响紫外光致发光峰红移和蓝移的可能机理.     

Si衬底上低真空热处理制备单一相Mg2Si半导体薄膜

采用磁控溅射沉积方法制备Mg2Si半导体薄膜。首先在Si衬底上沉积Mg膜,随后低真空热处理。采用X射线衍射、扫描电镜、拉曼光谱对Mg2Si薄膜的结构进行表征。研究了在低真空(10-1～10-2Pa)条件下热处理温度(350～550℃)和热处理时间(3～7h)对Mg2Si薄膜形成的影响。结果表明,低真空热处理条件下制备了单一相Mg2Si半导体薄膜,400～550℃热处理4～5h是最佳的热处理条件。在拉曼谱中256和690cm-1处观察到两个散射峰,这与Mg2Si的拉曼特征峰峰位一致。     

Microstructure evolution and photoluminescence in nanocrystalline Mg(x)Zn(1 - x)O thin films

The effects of Mg concentration and annealing temperature on the characteristics of nanocrystalline Mg(x)Zn(1 - x)O thin films (where x = 0-0.4) were studied using electron microscopy and photoluminescence. The films were prepared by a sol-gel method. The solid solubility limit of MgO in ZnO for the sol-gel-derived Mg(x)Zn(1 - x)O films in the present study was determined to be ～ 20 at.%. Microstructural characterization of the films showed that the wurtzite crystallites decrease in size with increase in Mg concentration up to the solubility limit. Increasing Mg concentration beyond the solubility limit resulted in a decrease in crystallinity of the films. The bandgap energy was found to increase with Mg concentration whereas the linewidth first increased and then decreased when the Mg concentration was increased beyond the solubility limit. Photoluminescence properties have been correlated to the microstructure of the films. A growth mechanism for Mg(x)Zn(1 - x)O nanocrystalline films under the present processing conditions has also been proposed.     

Anomalous elastic properties of RF-sputtered amorphous TeO2+x thin film for temperature-stable SAW device applications.

The anomalous elastic properties of TeO2+x thin films deposited by rf diode sputtering on substrates at room temperature have been studied. The deposited films are amorphous, and IR spectroscopy reveals the formation of Te-O bond. X-ray photoelectron spectroscopy confirms the variation in the stoichiometry of TeO2+x film from x=0 to 1 with an increase in the oxygen percentage in processing gas composition. The elastic parameters of the films in comparison to the reported values for TeO2+x single crystal are found to be low. However, the temperature coefficients of elastic parameters of all deposited films exhibit anomalous behavior showing positive values for TC(C11) in the range (32.0 to 600.0)x10(-4) degrees C(-1) and TC(C44)=(35.0 to 645.5)x10(-4) degrees C(-1) against the negative values TC(C11)=-2.7x10(-4) degrees C(-1) and TC(C44)=-0.73x10(-4) degrees C(-1) reported for TeO2+x single crystal. The variation in the elastic parameters and their temperature coefficients is correlated with the change in the three-dimensional network of Te-O bonding. The anomalous elastic properties of the TeO2+x films grown in 100% O2 are useful for potential application in the design of temperature stable surface acoustic wave devices.     

Growth kinetic and characterization of Mg(x)Zn1-xO nanoneedles synthesized by thermal oxidation

Mg(x)Zn1-xO nanoneedles were synthesized on alumina substrate by using thermal oxidation technique under normal atmosphere. Zn powder and MgO powder were mixed and heated to form Mg(x)Zn1-xO with x content of 0-0.3 by mol at heating temperature and time of 400-1000 degrees C and 24 h. The morphology of Mg(x)Zn1-xO nanoneedle was characterized by filed emission scanning electron microscope (FE-SEM). It was found that the needle-like nanostructures with the sharp ends were observed outward from microparticles at 400-800 degrees C. From EDS, XRD, and TEM analysis, it was suggested that Mg(x)Zn1-xO alloy was formed with no segregation of MgO in Mg(x)Zn1-xO alloy after thermal oxidation process. Also, from reflectance spectra, the Mg(x)Zn1-xO nanoneedle exhibited higher energy gap than that of ZnO films for entire Mg content indicating widening band gap energy due to alloying effect. Moreover, we have proposed the growth mechanism of Mg(x)Zn1-xO nanoneedles based on growth kinetic of nucleation formation. This growth model can be explored to explain nanostructure of other metal-oxide alloy prepared by thermal oxidation.     

溶胶-凝胶法制备MgxZn1-xO薄膜及性能研究

采用溶胶-凝胶法在石英玻璃片衬底上制备了Mg2+掺杂的ZnO(MgxZn1-xO)薄膜,研究了Mg2+掺杂对ZnO薄膜结构和紫外透过率的影响;在氧化物薄膜上真空蒸镀了Al叉指电极,制得紫外原型探测器件,测试了I-Ⅴ特性.结果表明,Mg2+掺杂后,MgxZn1-xO薄膜为纤锌矿结构,随着x值增加,晶格常数c逐渐减少,α逐渐增大,Mg2+掺杂抑制了(002)晶面的生长;紫外透过光谱表明,Mg2+掺杂后吸收边发生蓝移,可提高ZnO薄膜的禁带宽度;I-Ⅴ特性曲线表明,正向偏压下探测器的暗电流和光照电流随外加偏压呈线性增长,但光照电流与暗电流的差别较大.     

Growth and characterization of group-II-alloyed ZnAlO UV-range transparent conductive films prepared by RF magnetron sputtering

ZnAlO films alloyed with various group-II elements (Be, Mg, Ca, Sr) were sputter grown and its effects on the optical and electrical properties of the films were studied. It was observed that addition of Be most efficiently increases the Eg (∼3.8 eV) but results in high resistivity (0.5 Ωcm), while an addition of Mg resulted in a relatively low resistivity (∼7 × 10⁻⁴ Ωcm) and moderate increase in Eg (3.7 eV). Other films showed high resistivity (∼1 Ωcm) and relatively low Eg (3.5 eV for ZnSrAlO). It was proposed that the difference in the ionic radii between the alloying elements and the Zn host ion resulted in lattice strain and formation of non-conductive clusters, which would act as the trap centers and scattering centers, reducing the carrier density and the mobility.     

氧离子束辅助激光淀积生长ZnO/Si的XPS探究

为了探究ZnO/Si内部化学成分及有关信息,用氧离子束辅助(O+-assisted)脉冲激光淀积(PLD)法在不同实验条件下生长成ZnO/Si(111)样品.利用X射线光电子能谱(XPS)对长成的ZnO/Si异质结构进行了异位测试.通过对O1s峰及其肩状结构进行拟合、分析,得到了原子数密度比n(O)∶n(Zn),进而探究了原子数密度比与生长质量的关系.结果表明,用氧离子束辅助PLD法,可在较低的衬底温度190℃和适当O+束流条件下,生长出正化学比接近于1,且c轴单一取向最佳的ZnO/Si薄膜.用氧离子束辅助PLD淀积法生长ZnO薄膜,可以改善缺氧状况,能提供一个富氧环境.     

Mg/sub x/Zn/sub 1-x/O: a new piezoelectric material

Piezoelectric ZnO thin films have been successfully used for multilayer surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices. Magnesium zinc oxide (Mg/sub x/Zn/sub 1-x/O) is a new piezoelectric material, which is formed by alloying ZnO and MgO. Mg/sub x/Zn/sub 1-x/O allows for flexibility in thin film SAW device design, as its piezoelectric properties can be tailored by controlling the Mg composition, as well as by using Mg/sub x/Zn/sub 1-x/O/ZnO multilayer structures. We report the metal-organic chemical vapor deposition (MOCVD) growth, structural characterization and SAW evaluation of piezoelectric Mg/sub x/Zn/sub 1-x/O (x<0.35) thin films grown on (011~2) r-plane sapphire substrates. The primary axis of symmetry, the c-axis, lies on the Mg/sub x/Zn/sub 1-x/O growth plane, resulting in the in-plane anisotropy of piezoelectric properties. SAW test devices for Rayleigh and Love wave modes, propagating parallel and perpendicular to the c-axis, were designed and fabricated. Their SAW properties, including velocity dispersion and piezoelectric coupling, were characterized. It has been found that the acoustic velocity increases, whereas the piezoelectric coupling decreases with increasing Mg composition in piezoelectric Mg/sub x/Zn/sub 1-x/O films.     

低温生长Zn1-xCoxO(x=0.33)薄膜的微结构和磁性

用电子束反应蒸镀法在低温生长了Zn1-xCoxO薄膜.Co含量x高达0.33的Zn1-xCoxO薄膜仍具有类ZnO的纤锌矿结构,没有杂质相,Co的化合价为 2.场冷和零场冷M-T及M-H曲线表明,Zn1-xCoxO(x=0.33)薄膜在低温下具有铁磁性;随着温度的升高,其剩磁和矫顽力均逐渐下降,在65 K以上趋于零,显示出超顺磁性.Zn1xCoxO薄膜的低温铁磁性起源于Co2 离子之间的双交换相互作用及载流子诱导的sP d交换耦合作用,而从低温(＜65 K)铁磁态到高温(＞65 K)超顺磁态的转变可归因于薄膜的纳米晶小尺寸效应.     

Cd掺杂量对Zn1-xCdxO合金带隙的影响

回顾了国内外Zn1-xCdxO合金带隙研究的发展历程,总结和归纳了近10年来关于Zn1-xCdxO合金中Cd原子分数x与Eg(eV)关系的数据及理论等研究成果.在此基础上,以近10年来文献中的试验数据作为分析样本,考虑多种情况对其进行回归拟合,并对不同拟合方法及Cd含量对Eg的影响进行了深入的分析讨论,建立了Cd含量x与Eg的经验关系式(x-Eg关系式).与试验值相比,使用新xEg关系式预测得到的Eg值与其符合得较好,表明所建立的关系式能比较准确地反映Zn1-x CdxO合金中Cd含量x与Eg之间的关系.     

CoxR1-xAl2O4(R=Zn,Mg)钴蓝颜料反射性能的研究

采用化学共沉淀法成功地制备出适用于彩电显象管内荧光体着色的Ｃｏ_ｘＲ_１－ｘＡｌ_２Ｏ_４（Ｒ＝Ｚｎ、 Ｍｇ, ｘ＝０．８～１．０）钴蓝颜料： ４５０ｎｍ波长处反射率最大提高１８．２％, ６００ｎｍ处反射率最大降低５％。通过对该颜料反射率的影响因素,如掺杂离子类型、掺杂浓度和Ｃｏ^２＋离子浓度的探讨,结论如下：Ｚｎ^２＋、Ｍｇ^２＋改变钴蓝颜料反射性能的作用机理为晶格畸变引起Ｃｏ^２＋３ｄ轨道电子能级分裂程度的变化;对于掺杂离子Ｚｎ^２＋、Ｍｇ^２＋,ｘ下限值分别约为０．８５和０．８．