采用MOCVD方法在GaAs衬底上生长ZnO(002)和ZnO(100)薄膜

采用金属有机化学汽相沉积生长法（MOCVD）,在不同的衬底表面处理条件和生长温度下,在GaAs衬底上生长出了ZnO薄膜。随着化学腐蚀条件的不同,可生长出优先定位不同的ZnO（100）和ZnO（002）薄膜。该薄膜的晶体结构特性是由X光衍射谱仪（XRD）所获得的,而其光学特性是由光荧光谱仪（PL）来测的。与ZnO（002）相比,ZnO（100）薄膜具有更优越的晶体结构特性,并且在同样的生长温度下都具有相似的光学特性。对于腐蚀条件不同的GaAs衬底所进行的XPS分析结果表明,ZnO薄膜优先定位变化的主要原因在于腐蚀过程中形成的富As层。     

Growth control of stoichiometry in LaMnO3 epitaxial thin films by pulsed laser deposition

We have studied structural, magnetic, and optical transport properties of LaMnO₃ (LMO) thin films grown on SrTiO₃. While the stoichiometric LMO is an insulating antiferromagnet, it tends to be a ferromagnetic insulator when grown as thin films. By exploring the majority of growth parameters, we have found that the bulk-like electronic and magnetic phases can be stabilized by growing thin films under reducing atmospheres and by using more energetic laser processes. These conditions are found to reduce the La deficiency in the film resulting in the greatly improved cation stoichiometry. Since oxides are prone to reduce the oxygen content and to alter the cation ratio under such growth conditions, it suggests that the cation and oxygen stoichiometries in complex oxide thin films can be improved by properly optimizing the growth parameters.     

Structural and electrical properties of CdS thin films evaporated onto GaAs substrates

CdS thin films on GaAs substrates are prepared by single source thermal evaporation under high vacuum conditions. Films on (111)A-oriented substrates have the wurtzite structure, whereas in the case of (1 1 1 )B-oriented substrates the sphalerite structure predominates. Depositing films on pre-annealed substrates a tetragonal phase with a composition near CdGa₂S₄ was found. The electron concentration in the CdS films is influenced by the substrate temperature, the growth rate of the films, and the substrate orientation.     

Influence of electron beam annealing on optical properties of a-Si from ellipsometric spectrum study

The optical properties of a-Si films prepared by rf sputtering and annealed by an electron beam under different conditions have been measured by the spectroscopic ellipsometry technique in the ultraviolet-visible range. The results show that the optical properties of these samples obviously changed with suitable annealing conditions, and the amorphous silicon can be gradually transformed to crystalline silicon.     

Formation of ultrasmooth thin silver films by pulsed laser deposition

Ultrasmooth thin silver films have been formed on a quartz substrate with a buffer yttrium oxide layer by pulsed laser deposition. The dependence of the surface morphology of the film on the gas (N₂) pressure in the working chamber and laser pulse energy is investigated. It is found that the conditions of film growth are optimal at a gas pressure of 10^?2 Torr and lowest pulse energy. The silver films formed under these conditions on a quartz substrate with an initial surface roughness of 0.3 nm had a surface roughness of 0.36 nm. These films can be used as a basis for various optoelectronics and nanoplasmonics elements.     

Characterisation of porosity and sensor response times of sol-gel-derived thin films for oxygen sensor applications

In recent years, sol-gel-derived films have played a significant role in optical sensor development. This paper focuses on the characterisation of oxygen-sensitive tetraethoxysilane (TEOS) and methyltriethoxysilane (MTEOS)-based films. Film porosity and sensor response times are reported for a range of films fabricated under different conditions. Porosity data are correlated with predicted film behaviour and also with previous characterisation studies. Oxygen diffusion coefficients are estimated from the response times. The enhanced diffusion coefficient of MTEOS films compared to TEOS films is discussed in terms of the relative oxygen solubility of the films. Comparisons are made with data for oxygen-sensitive polymer films, indicating an enhanced solubility for sol-gel films compared with typical polymer films.     

钨酸盐薄膜的原电池电化学制备技术及其发光性能

采用室温原电池电化学技术在钨衬底上制备出了具有发光性能的BaWO4、SrWO4、CaWO4薄膜,利用X射线衍射仪、扫描电镜、荧光光谱仪对样品进行了分析,对薄膜的发光性能进行了研究。XRD分析表明,所制备的钨酸盐薄膜是高度结晶的,呈四方结构;SEM观察表明,在原电池条件下,这些晶体以四方锥形的习性生长。室温下的荧光性能测试表明,所制备的BaWO4、SrWO4、CaWO4薄膜在220nm至240nm的光激发下,均在450nm附近出现一个蓝光发射带,而BaWO4薄膜还在310nm的光激发下,在400nm及590nm附近出现额外的发射带,形成从400~590nm的准连续发射光谱。研究表明,原电池电化学技术为某些功能陶瓷薄膜的制备提供了一条环境协调的、廉价便利的工艺新路线。     

Influence of thermal annealing ambient on Ga-doped ZnO thin films

The effect of thermal annealing on the structural, chemical, electrical, and optical properties of Ga-doped ZnO (GZO) films was investigated in various ambients, such as oxygen, nitrogen, and forming gas (95% N₂ 5% H₂). The variation of these properties is thought to be related to the chemisorption and removal of adsorbed oxygen on the GZO film surface. The carrier concentration of the GZO films increased with heat treatment in the forming gas ambient. However, the carrier concentration of the GZO films decreased with heat treatment in oxygen and nitrogen. Annealing under forming gas, oxygen weakly absorbed on the GZO film was removed. Annealing under N- and O-rich conditions, chemisorption of oxygen was dominant. These results were clarified by comparatively analyzing the chemical states of oxygen on the surface of the GZO films.     

PbI2多晶膜的制备及其晶体结构

采用电子束蒸发法制备PbI2多晶膜,研究了制备条件对沉积速率和晶体结构的影响.结果表明,源-衬间距和衬底温度对沉积速率的影响不具单调性,沉积速率随源-衬间距增大、衬底温度升高呈波动起伏.不同条件下制备的PbI2膜均属六方结构,但结晶质量和择优生长晶面存在差异.实验发现,随着膜层厚度增大,样品的结晶质量提高,当膜厚超出某一临界值,其结晶质量出现明显的下降.同时,随着衬底温度升高,PbI2膜的择优生长方向由80 ℃的(110)晶面转变为120 ℃的(001)晶面,且高级次(002)、(003)、(004)晶面的衍射峰逐渐增强,样品的c轴择优取向生长更加明显.综合以上,在电子枪束流25 mA、电压6.5 kV,源-衬间距30 cm、衬底温度160 ℃的条件下,采用电子束蒸发制备的PbI2多晶膜具有最佳的结晶性能.     

溅射法制备YAG:Ce3+荧光薄膜

以自制铈掺杂立方相钇铝石榴石(YAG∶Ce3+)荧光粉为原料经冷静压压制得到粉末靶材,在纯氩气气氛下通过射频磁控溅射法在石英玻片上镀膜,随后在氩气气氛下1100℃/3 h热处理得到YAG∶Ce3+荧光薄膜。系统探讨了溅射功率、靶间距等因素对YAG∶Ce3+荧光薄膜物理和发光性能的影响。分析发现采用粉末靶可以明显提高YAG∶Ce3+薄膜溅射沉积速率,在靶间距20 mm,溅射功率300 W的制备条件下得到的荧光薄膜经450 nm蓝光激发时,可发射524 nm的光,较商用荧光粉发射峰略有蓝移。粉末靶溅射制备荧光薄膜具有大规模实际应用潜力。     

High-quality diamond films grown at high deposition rates using high-power-density MWPCVD method with conventional quartz-type chamber

Undoped and boron-doped homoepitaxial diamond films with high quality have been successfully grown on high-pressure/high-temperature-synthesized type-Ib single-crystalline diamond (1 0 0) substrates. In the growth process, a conventional microwave-plasma (MWP) chemical-vapor-deposition (CVD) system with an easily-exchangeable 36-mm-inner-diameter quartz-tube growth chamber was employed under a condition of high MW power densities while a rather high methane concentration (4%) and high substrate temperatures (>1000 °C) were used. The growth conditions applied to the undoped and B-doped diamond thin films were separately optimized by controlling the MW plasma density and substrate temperatures. The homoepitaxial films thus grown yielded strong exciton-related luminescence even at room temperature, meaning that their crystalline quality was good and roughly comparable with that of homoepitaxial films deposited using a high-power MWPCVD system with a stainless steel chamber having a rather large diameter. This indicates that by using such a conventional deposition system with inexpensive and easily-exchangeable exclusive-use quartz-tube chambers, various growth experiments can be performed under different process conditions without any severe interference among the different experiments.     

Bildungsbedingungen und Struktur dünner Bi1−xSbx-Schichten

Thin polycrystalline Bi_1−xSb_x films in oriented state were deposited by flash evaporation techniques and by catode sputtering. In dependence on the conditions of formation the structure of these films was analysed by means of transmission electron microscopy, electron diffraction and electron beam microanalysis. Estimating the orientation, quality of surface and largeness of the average diameter of the crytallites the flash evaporation technique is superior to the catode sputtering under the experimental conditions chosen in this investigation. The Bi:Sb proportion does not change in comparison with the target, material of the source respectively, during the formation of the film.     

The evolution of bond structure in Ge33As12Se55 films upon thermal annealing

The evolution of bond structure of laser deposited Ge₃₃As₁₂Se₅₅ films under various processing conditions has been investigated by X-ray photoelectron spectroscopy. It was found that a large number of Se-rich structures in the as-grown film may coalesce with As and Ge after annealing at high temperatures. In addition, both Ge and As 3d spectra show the presence of oxides. The oxygen distribution exponentially decays along the normal direction of the films regardless of different processing conditions. The critical thickness of the oxidized layer was extracted for the film annealed at various pressures and temperatures.     

Effect of Thermal Annealing on Structural Properties,Morphologies and Electrical Properties of TiO2 Thin Films Grown by MOCVD

TiO₂ thin films, were deposited on Si(100) and Si(111) substrates by metalorganic chemical vapor deposition at 500 °C, and have been annealed for 2 min, 30 min and 10 hours at the temperature from 600 °C to 900 °C, in oxygen and air flow, respectively. XRD and atomic force microscopy characterized the structural properties and surface morphologies of the films. As‐deposited films show anatase polycrystalline structure with a surface morphology of regular rectangled grains with distinct boundaries. Rutile phase formed for films annealed above 600 °C, and pure rutile polycrystalline films with (110) orientation can be obtained after annealing under adequate conditions. Rutile annealed films exhibit a surface morphology of equiaxed grains without distinct boundaries. The effects of substrate orientation, annealing time and atmosphere on the structure and surface morphology of films have also been studied. Capacitance‐Voltage measurements have been performed for films deposited on Si(100) before and after annealing. The dielectric properties of TiO₂ films were greatly improved by thermal annealing above 600 °C in oxygen.     

Growth of epitaxial thin films of scandium nitride on 100-oriented silicon

A series of 100-oriented ScN films was grown under N-rich conditions on 100-oriented Si using different Sc fluxes. The ScN films grew in an epitaxial cube-on-cube orientation, with [0 0 1]_ScN//[0 0 1]_Si and [1 0 0]_ScN//[1 0 0]_Si, despite the high (11%) lattice mismatch between ScN and Si. The film grain size increases and the film ω-FWHM decreases with increasing Sc flux, but the film roughness increases. Films grown under similar conditions on 111-oriented Si resulted in mixed 111 and 100 orientations, indicating that the 100 orientation is favoured both due to texture inheritance from the substrate and due to the growth conditions used.     

电子辅助热丝化学气相沉积金刚石薄膜中氢原子谱线与最佳成膜条件

采用蒙特卡罗方法,对以CH4／H2混合气体为源气体的EACVD中的氢原子发射过程进行了模拟。研究了不同实验条件下产生的H、CH3的数目与氢原子谱线相对强度的关系,给出了一种利用氢原子谱线来获得最佳成膜实验条件的方法。本工作对于有效控制工艺条件,生长出高质量的金刚石薄膜具有重要意义。     

Complex study of mechanical properties of a-Si:H and a-SiC:H boron doped films

The aim of the present work is to provide the complex study of the mechanical properties of p-doped a-Si:H and a-SiC:H thin films prepared under different plasma conditions. For the investigation of the samples we used mainly the continuous depth sensing indentation technique (DSI), pin-on-disc test and internal stress measurement. The morphology of the thin film surface and the indentation prints are studied using optical microscopy, scanning electron microscopy (SEM) and topography mode of atomic force microscopy (AFM). The dependence of the mechanical parameters upon the deposition conditions were compared with the optoelectronic properties of studied films.     

Preparation of indium tin oxide thin films without external heating for application in solar cells

Indium tin oxide (ITO) films were grown without external heating in an ambient of pure argon by RF-magnetron sputtering method. The influence of argon ambient pressure on the electro-optical properties of as-deposited ITO films was investigated. The morphology, structural and optical properties of ITO films were examined and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and UV–VIS transmission spectroscopy. The deposited ITO films with a thickness of 300 nm show a high transparency between 80% and 90% in the visible spectrum and 14–120 Ω/□ sheet resistance under different conditions. The ITO films deposited in the optimum argon ambient pressure were used as transparent electrical contacts for thin film Cu(In,Ga)Se₂ (CIGS) solar cells. CIGS solar cells with efficiencies of the order of 7.0% were produced without antireflective films. The results have demonstrated that the developed ITO deposition technology has potential applications in thin film solar cells.     

Epitaxial growth of MgO films on Si(1 1 1) by metal organic chemical vapor deposition

Epitaxial MgO films were grown on Si(1 1 1) substrates at 800°C using methylmagnesium tert-butoxide (MeMgO^tBu) as a single precursor under high-vacuum conditions (5×10⁻⁶ Torr). The crystalline structure, morphology, and chemical composition of the deposited films were investigated by X-ray diffraction, X-ray pole figure analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results show that epitaxial MgO films with correct stoichiometry can be deposited on Si(1 1 1) at 800°C. The single precursor methylmagnesium tert-butoxide has been found suitable for the epitaxial growth of MgO on Si(1 1 1) substrates.     

射频溅射功率对Mn-Co-Ni-O薄膜结构与性能的影响

采用射频磁控溅射技术在硅衬底上制备了锰钴镍氧(Mn-Co-Ni-O, MCNO)薄膜并进行了后退火处理。利用X射线衍射、扫描电子显微镜、光学测试仪器等测试手段对晶体结构、表面形貌及光学性能进行表征。分析了不同射频溅射功率(60~100 W)对MCNO薄膜表面微观形貌、晶体结构和光学性能的影响。结果表明,在60~90 W下获得的薄膜表面致密且均匀,但在100 W下获得的MCNO薄膜表面晶粒尺寸显著增大。物相分析表明,采用射频磁控溅射沉积的MCNO薄膜主要为尖晶石结构,溅射功率对薄膜结晶质量和择优取向具有显著影响,在80 W下获得的MCNO薄膜结晶质量最佳。同时,拉曼光谱测试也表明该MCNO薄膜表现出最强的Mn⁴⁺—O对称弯曲振动和最小的压应力。紫外-可见-近红外光谱分析表明,MCNO薄膜的吸光范围主要在可见光-近红外波段,在80~90 W溅射功率下获得的MCNO薄膜在近红外波段表现出更强的吸收峰。射频溅射功率的改变会影响薄膜的厚度和结晶质量,从而对薄膜的光学带隙起到调控作用。光致发光光谱测试不同溅射功率下薄膜的缺陷峰发光强度,且在功率为80 W时沉积的薄膜具有最强紫外发射峰,表明改变溅射功率能够有效改善薄膜缺陷及提高晶体质量。