Optical properties of NiO thin films fabricated by electron beam evaporation

Nickel oxide (NiO) thin films were deposited onto quartz substrates by the electron beam deposition technique, and obtained high crystal quality after annealing at 1173 K. The structural and microstructural properties of the films were studied by X-ray diffraction (XRD) and atomic force microscope (AFM), respectively. We focus on the optical characterization of the films, indicating the enhancement of the crystal quality, which was confirmed by the photoluminescence and Raman spectrum. Furthermore, PL studies exhibited room temperature emission at 377 nm, and also shown high ultraviolet/visible rejection ratio (>100).     

Effect of different atmospheres on the electrical stabilization of NiO films

Sputtered nickel oxide (NiO) films have a wide range of applications including their use in transparent conductive anodes for organic light-emitting diodes (OLEDs) where stable electrical properties are essential. Unfortunately, NiO films show electrical aging phenomenon in air. In the present experiments, the phenomenon of aging was investigated in different atmospheres including H₂, CO, O₂, CO₂, N₂, and Ar together with varying the humidity. It was found that NiO films were relatively stable in Ar but very unstable in H₂, CO and humid argon atmospheres. The aging rate increased rapidly as the humidity was increased from 2 to 20 relative humidity (RH) and became constant from 20 to 40 RH.     

MOCVD法制备SnO2单晶薄膜的结构和光学性质

用金属有机物化学气相沉积（MOCVD）法在蓝宝石（0001）衬底上制备出高质量的氧化锡（SnO2）单晶薄膜。对制备薄膜的结构和光学性质进行了研究。制备样品具有纯snO2的四方金红石结构，其外延生长方向为SnO2（100）∥Al2O3（0001）。薄膜均匀、致密，具有很好的取向性和结晶性。透射谱测量结果表明，在可见光区薄膜的绝对透过率达到了90％以上。     

衬底温度对磁控溅射制备外延ZnO薄膜结构特性的影响

在不同的衬底温度下,采用磁控溅射方法在蓝宝石(0001)衬底上制备了外延生长的ZnO薄膜.采用原子力显微镜(AFM)、X射线衍射仪(XRD)、可见-紫外分光光度计系统研究了衬底温度对ZnO薄膜微观结构和光学特性的影响.AFM结果表明在不同村底温度制备的ZnO薄膜具有较为均匀的ZnO晶粒,且晶粒的尺寸随衬底温度的增加逐渐增大.XRD结果显示不同温度生长的ZnO薄膜均为外延生长,400℃生长的薄膜具有最好的结晶质量;光学透射谱显示在370nm附近均出现一个较陡的吸收边,表明制备的ZnO薄膜具有较高的质量,其光学能带隙随着衬底温度的增加而减小.     

用脉冲电沉积法制备两类纳米介孔氧化镍电致变色薄膜的研究

采用脉冲电沉积技术在ITO导电玻璃上制备了NiO电致变色薄膜,并用X射线衍射仪、扫描电镜和能谱仪分析薄膜的结构、形貌和成份,用紫外-可见光分光光度计测试薄膜的光学性能,用循环伏安法测试薄膜的电化学性能,对比研究了Co掺杂对NiO薄膜电致变色性能的影响。结果表明Co掺杂优化了NiO薄膜表面形貌,形成了均匀分布的纳米介孔微结构,从而提高了薄膜电化学活性,同时提高了薄膜的光调制幅度。     

NiO/Al体系绝热温度的数值计算与试验验证

根据热力学基本原理, 通过计算机编程, 对NiO/Al体系的绝热温度进行了数值计算。结果表明, 预热温度低于2790 K时, 体系绝热温度即为产物Ni 的沸点温度(3156 K) , 对体系进行预热仅仅是提高产物Ni 的蒸发量; 同时, 研究表明, 稀释剂Al2O3粉末的添加量在一定的范围内对体系的绝热温度没有影响, 这些温度与生成物的相变温度相对应。      

Preparation and properties of p-type transparent conductive Cu-doped NiO films

The NiO-Cu composite films with various Cu contents of 0-18.17 at.% are deposited on a glass substrate. An ultra high electrical resistivity (ρ) is obtained and cannot be detected by a four point probe measurement when the Cu content in the films is lower than 6.97 at.%. The ρ value is reduced significantly to 35.8 Ω-cm as Cu content is increased to 9.18 at.%, and it further decreases to 0.02 Ω-cm when the Cu content further increases to 18.17 at.%. The Hall measurement for all Cu-doped NiO films shows p-type conduction. In addition, the transmittance of NiO films also decreases continuously from 96% to 43% as Cu content increases from 0 to 18.17 at.%. The XRD patterns of Cu-doped NiO films show that only NiO peaks appear and the crystallinity of NiO films degrades as Cu content exceeds 6.97 at.%. A large amount of lattice sites of Ni²⁺ ions in a NiO crystallite is replaced by the Cu⁺ ions that lead to p-type conduction and result in the degradation of crystallinity for NiO-Cu composite films that have a higher Cu content.     

Influences of process parameters on texture and microstructure of NiO films

The experimental result shows that the preferred orientations of NiO thin films are closely related to the working pressure of argon. All of NiO(111), NiO(200), and NiO(220) diffraction peaks are observed in the XRD patterns and exhibited random orientation of NiO film when the film is deposited in low Ar pressure of 0.67 Pa. As the Ar pressure is increased to 2.67 Pa, only the NiO(200) peak appears and shows (200)-textured NiO films. However, the lattice parameter of NiO film deposited in high Ar pressure of 2.67 Pa is 0.426 nm, which is much larger than that of the NiO bulk (0.417 nm). The lattice parameter can be reduced by post-annealing the film because the interstitial Ar atoms are released from the NiO lattice, decreasing continuously from 0.423 to 0.417 nm as the NiO films are annealed by rapid thermal annealing (RTA) from 300 to 600 °C.     

温度对电沉积的SnS薄膜的结构和性能的影响

在溶液的pH=2.7,离子浓度比Sn2 /S2O32-=1/5,沉积电位为-0.72～-0.75V(vs.SCE)的条件下,控制溶液的温度在30～50℃之间变化,用阴极恒电位电沉积法在ITO导电玻璃基片上沉积SnS薄膜.通过对薄膜的结构和光学性能研究,结果表明:溶液的温度越高,制备出的SnS薄膜更加致密,均匀,薄膜的衍射峰也越来越明显;同时SnS薄膜对光的吸收范围也向长波方向拓宽.     

Studies of influence of structural properties and thickness of NiO thin films on formaldehyde detection

The aim of the present work is to test the performance of nickel oxide (NiO) thin films to low concentrations of formaldehyde (HCHO). NiO thin films were deposited on alumina substrates by RF reactive magnetron sputtering in a mixed atmosphere of argon and oxygen. A Pt heating resistor was deposited on the reverse side for an accurate control of the operating temperature. Samples were annealed in synthetic air for 4 h at 700 °C in order to stabilise their microstructure. Two different thicknesses (150 and 300 nm) were deposited in order to study the influence of this parameter on both the microstructure and sensor response. Both XRD analysis and FEG-SEM images show a smaller grain size for the 150 nm-thick samples. The best operating temperature was established at 340 and 300 °C for 150 and 300 nm-thick samples respectively. A higher sensitivity was obtained for the samples of lower thickness for a set of HCHO concentrations ranging from 5 to 20 ppm. Moreover, the repeatability of the experiments was tested for the most sensitive samples.     

生长温度对InAs/GaAs横向异质结构纳米线形貌及晶体结构的影响

低维半导体材料因其超常的物理性能而受到了广泛关注和研究。本文采用金属有机物化学气相沉积（MOCVD）技术,利用金作催化剂制备了InAs/GaAs横向异质结构纳米线,并讨论了不同生长温度情况下InAs横向异质材料对纳米线形貌及晶体结构的影响。提高InAs材料的生长温度,可以有效地抑制纳米线的纵向生长,使其实现横向异质结构的生长。在异质结构纳米线横向生长时发生了侧面晶面旋转的现象,这是纳米线表面重构后侧面趋向能量更低的晶面的结果。本文的研究工作为推动微纳技术的发展提供了相应的理论基础和科学依据。      

Influence of deposition temperature on the structure and optical properties of HfO2 thin films

Hafnium oxide (HfO₂) thin films were deposited on Si (001) substrates by electron beam evaporation at various growth temperatures. It was found that the film was amorphous when deposited at temperatures lower than 200°C. It was polycrystalline when deposited at 250°C and 300°C. At temperatures above 400°C, it was grown preferably along the [111] direction. The influence of growth temperature on the surface morphology and optical property was also investigated.     

Transparent p-type conducting K-doped NiO films deposited by pulsed plasma deposition

Transparent p-type conducting K-doped NiO thin films were prepared by pulsed plasma deposition. The structural, electrical and optical properties of the films were investigated using X-ray diffraction, atomic force microscope, X-ray photoelectron spectroscopy, Hall measurement, and ultraviolet-visible spectroscopy, respectively. The dependency of film properties on K doping content and substrate temperature was studied. The film with K doping content of 25 at.% deposited at room temperature exhibits the highest conductivity of 4.25 S cm^− 1 and an average transmittance of nearly 60% in visible light region.     

Influence of VI/II ratios on the growth of ZnO thin films on sapphire substrates by low temperature MOCVD

We investigated the structural, electrical, and optical properties of ZnO thin films grown at different VI/II ratios on sapphire substrates by metalorganic chemical vapor deposition. Transmission electron microscopy and X-ray diffraction revealed the epitaxial nature with a reduced dislocation density of the ZnO films grown at increased VI/II ratios. The carrier concentration of the films increased to 4.9 × 10¹⁸ cm^− 3 and their resistivity decreased to 1.4 × 10^− 1 Ω cm at a VI/II ratio of 513.4 μmol/min. The ZnO films also showed good optical transmittance (> 80%) in the visible and near-infrared wavelength regions. The room temperature PL revealed a strong band-edge emission with a weak deep level emission, suggesting the good crystalline quality of the ZnO films on the sapphire substrates. Furthermore, the intensity ratio of the band-edge emission to the deep-level emission (I_UV/I_Vis) increased with increasing VI/II ratio.     

超高温传感器用感温材料与结构特性分析

针对现有蓝宝石光纤温度传感器测温上限难以突破1 700℃的瓶颈问题,本文分别从传感器测温结构和感温材料两方面进行了分析改进,以满足对2 000~2 500℃超高温的测量需求.提出了一种接触-非接触相结合的新型传感器测温结构,并结合非接触式测温结构特点给出了Plank黑体辐射温度误差补偿公式,解决了非接触结构的准确测温问题.结合不同感温材料特性分别对难熔金属、陶瓷基复合材料和C/C复合材料的高温性能进行分析比较,包括材料强度、密度、抗氧化性、塑性、熔点等,筛选出适合作为超高温传感器的备选感温材料.针对筛选出的感温材料设计了抗热震性试验和抗氧化烧蚀试验,实验结果表明Hf B2-Si C复合材料能够满足超高温环境下对感温材料物理特性的特殊需求.传感器温度试验结果表明,采用接触-非接触式新结构和Hf B2-Si C感温材料的新型光纤温度传感器可对2 500℃高温进行长时间稳定测量,测量精度达到±1%.     

Effect of substrate temperature on the optical parameters of thermally evaporated Ge-Se-Te thin films

Thin films of Ge₁₀Se_90 − xTe_x (x = 0, 10, 20, 30, 40, 50) glassy alloys were deposited at three substrate temperatures (303 K, 363 K and 423 K) using conventional thermal evaporation technique at base pressure of ~ 10^− 4 Pa. X-ray diffraction results show that films deposited at 303 K are of amorphous nature while films deposited at 363 K and 423 K are of polycrystalline nature. The optical parameters, refractive index and optical gap have been derived from the transmission spectra (using UV-Vis-NIR spectrophotometer) of the thin films in the spectral region 400-1500 nm. This has been observed that refractive index values remain almost constant while the optical gap is found to decrease considerably with the increase of substrate temperature. The decrease in optical gap is explained on the basis of change in nature of films, from amorphous to polycrystalline state, with the increase of substrate temperature. The optical gap has also been observed to decrease with the increase of Te content.     

Li和Ti共掺NiO薄膜的溶胶-凝胶法制备及其介电性能

采用溶胶-凝胶法在Pt/Ti/SiO2(1mm)/Si基板上制备了Li和Ti共掺NiO基新型无铅介电薄膜材料,研究了薄膜的形貌、结构、介电性能.结果表明,热分解温度(300～500℃)对薄膜结构影响不明显,经600～800℃退火后的薄膜由NiO与Li-Ni-O复合氧化伆组成;经300℃热分解处理、650℃退火后的薄膜,其表面均匀致密,膜厚约300nm,室温下100Hz时的介电常数为767,当频率高于3000Hz后,介电常数随频率的增加趋于减小.     

醇-水法制备纳米晶NiO粉体

Ni(NO3 ) 2 ·6H2 O和NH4HCO3 在醇 水溶液中反应合成NiCO3 · 2Ni(OH) 2 ·2H2 O前驱体 ,经煅烧后得到大约 10nmNiO粉体。同传统的水溶液法相比 ,醇 水法得到的NiO粉体粒径尺寸小、分布范围窄和团聚少 ,PEG的添加能够减少团聚     

Effect of synthesis method on the physical and catalytic property of nanosized NiO

Nanosized NiO material was prepared by four different methods. Their physicochemical properties were investigated through SEM, BET, XRD and O₂-TPD characterization. The results indicated that NiO nanoparticles synthesized by different methods have variant diameters, shape and distribution. And the particles size and surface area influence the adsorptive and catalytic property. Therein nanosized NiO prepared by sol-gel method exhibits strong adsorptive property and good low temperature catalytic behavior.