Simulation of the thin-film thickness distribution for an OLED thermal evaporation process

A design of an OLED (organic light-emitting device) fabrication system strongly depends on a thermal evaporation process. In an OLED evaporation process, the essential requirements include good uniformity of the film thickness over a glass substrate. In this paper, a process simulation model was developed to predict the film thickness distribution by understanding system design parameters that affect the uniformity of film thickness. Based on the method developed in this study, the uniformity of the thickness in an organic layer was successfully controlled. The developed method allowed the manufacture of high quality OLED displays.     

CuInS2薄膜的单源热蒸发制备及其性能研究

本文以烧结合成的CuInS2粉末为原料,采用单源热蒸发技术在玻璃基底上沉积CuInS2薄膜。随着退火温度的升高,薄膜的结晶性能增强,表现出高度的(112)晶面择优取向,SEM观察显示:350℃退火后,薄膜致密,晶粒细小,大小为数十纳米。同时,热探针测试发现:薄膜的导电类型为弱N型。光学性能方面,当退火温度高于250℃时,CuInS2薄膜的禁带宽度为1.50 eV,接近吸收太阳光谱所需的理想禁带宽度值。     

真空热蒸发镀CIAS薄膜

采用真空热蒸发方法在普通玻璃基底上制备Cu In0.7Al0.3Se2(CIAS)薄膜,并对之进行450℃真空硒化退火处理。结果表明,制备的CIAS薄膜具有黄铜矿结构并且以(112)晶面优先生长。真空硒化退火后,薄膜晶体结构更完整,晶粒长大,成分分布均匀,更接近CIAS晶体的化学计量比。薄膜为P型半导体,退火后的薄膜禁带宽度减小至1.38 e V,带电粒子数下降至2.41E+17 cm-3,带电粒子迁移率增加至5.29 cm2/(N·s),电阻率升高至4.9Ω·cm。     

Improved performance of fluorinated copper phthalocyanine thin film transistors using an organic pn junction: Effect of copper phthalocyanine film thickness

We have investigated the effect of film thickness of copper phthalocyanine (CuPc) on improving fluorinated copper phthalocyanine (F₁₆CuPc) thin film transistor (TFT) performance with an organic pn junction. Electron field-effect mobility is exponentially enhanced up to 2.0 × 10^− 2 cm² V^− 1 s^− 1 with increasing of CuPc film thickness, and then unchanged when the CuPc thickness is over the saturation thickness (3 monolayers). The charge carrier density at the interface of F₁₆CuPc/CuPc decreases the total TFT resistance, which leads to the increase of mobility. Threshold voltage is suppressed with increasing CuPc films. On the other hand, larger current on/off ratio is obtained when islanded CuPc films are formed on the surface of F₁₆CuPc films. Therefore, employing an organic pn junction is an effective and simple method to fabricate high performance of n-channel transistors for practical applications.     

Grain size increase in pentacene thin films prepared in low-pressure gas ambient

We studied a mechanism of grain size increase (that is, island density decrease) in pentacene film prepared in hydrogen (H₂) ambient. The island densities of pentacene films prepared in helium and deuterium were lower than those of vacuum-deposited films. This indicates that the decrease in the island density was not due to the chemical interaction between H₂ and pentacene or the substrate surface. Furthermore, the temperature dependence of the island density indicates that there is no difference in the surface diffusion energy in a vacuum and in H₂. We also improved mobility significantly in the pentacene thin film transistor fabricated on film grown in H₂ ambient on a chemically treated substrate.     

On morphological, structural and electrical properties of vacuum deposited pentacene thin films

Films of different thickness (50, 100, 150 and 200 nm) were deposited by thermal evaporation in vacuum on two types of substrates glass and ITO. The deposition was performed under a pressure of 10⁻⁶ mB with a rate of 0.25 nm/s. Films surface investigations showed morphological and structural changes in function of films thickness and the nature of the substrate. Films optical transmission was analysed in the 280-1600 nm spectral range and the electrical measurements were done in low vacuum (10⁻¹:10⁻² mB) and in dark.     

氧化物异质外延薄膜生长的计算机模拟

利用Monte Carlo方法分别模拟了在SrTiO3基底上沉积MgO薄膜和在MgO基底上沉积SrTiO3薄膜.模拟中,选取与实验中薄膜生长相近的参数条件,引入了新的参数扩散势垒,得到了在晶格正失配(张应力)和负失配(压应力)下薄膜生长的形貌图以及薄膜粗糙度的变化曲线图,分析了张应力和压应力对薄膜生长形貌的影响.模拟结果与文献报道的外延薄膜生长模式的实验观察结果一致.     

Kinetic Monte Carlo模拟PVD薄膜生长的算法研究

提出kinetic Monte Carlo模拟物理气相沉积（physical vapor deposition,简写为PVD）薄膜生长的新算法：用红黑树搜索实现跃迁路径选择及系统跃迁概率更新,通过比较红黑树搜索、线性查找、满二元树搜索的计算效率,综合分析了这3种方法的时间复杂度和空间复杂度.结果表明红黑树搜索优于其它两种搜索方法,模拟效率最高,更适合用于执行大系统的kinetic Monte Carlo模拟.     

Structural, electrical, and optical properties of copper indium diselenide thin film prepared by thermal evaporation method

Stoichiometric compound of copper indium diselenide (CuInSe₂) was synthesized by direct reaction of high-purity elemental copper, indium and selenium in an evacuated quartz ampoule. The phase structure and composition of the synthesized pulverized material analyzed by X-ray diffraction (XRD) and energy dispersive analysis of X-rays (EDAX) revealed the chalcopyrite structure and stoichiometry of elements. Thin films of CuInSe₂ were deposited onto organically cleaned soda lime glass substrates held at different temperatures (i.e. 300 K to 573 K) using thermal evaporation technique. CuInSe₂ thin films were then thermally annealed in a vacuum chamber at 573 K at a base pressure of 10^− 2 mbar for 1 h. The effect of substrate temperature (T_s) and thermal annealing (T_a) on structural, compositional, morphological, optical and electrical properties of films were investigated using XRD, transmission electron microscopy, EDAX, atomic force microscopy (AFM), optical transmission measurements and Hall effect techniques. XRD and EDAX studies of CuInSe₂ thin films revealed that the films deposited in the substrate temperature range of 423-573 K have preferred orientation of grains along the (112) plane and near stoichiometric composition. AFM analysis indicates that the grain size increases with increase of T_s and T_a. Optical and electrical characterizations of films suggest that CuInSe₂ thin films have high absorption coefficient (10⁴ cm^− 1) and resistivity value in the interval 10^− 2-10¹ Ω cm influenced by T_s and T_a.     

Molecular layer deposition of ZrO2-based organic-inorganic nanohybrid thin films for organic thin film transistors

Molecular layer deposition (MLD) technique can be used for preparation of various organic-inorganic nanohybrid superlattices at a gas-phase. The MLD method is a self-controlled layer-by-layer growth process under vacuum conditions, and is perfectly compatible with the atomic layer deposition (ALD) method. In this paper, we fabricated a new type organic-inorganic nanohybrid thin film using MLD method combined with ALD. A self-assembled organic layer (SAOL) was formed at 170 °C using MLD with repeated sequential adsorptions of CC terminated alkylsilane and zirconium hydroxyl with ozone activation. A ZrO₂ inorganic nanolayer was deposited at the same temperature using ALD with alternating surface-saturating reactions of Zr(OC(CH₃)₃)₄ and H₂O. The prepared SAOL-ZrO₂ organic-inorganic nanohybrid films exhibited good mechanical stability, excellent insulating properties, and relatively high dielectric constant k (~ 16). They were then used as a 23 nm-thick dielectric for low voltage pentacene-based thin film transistors, which showed a maximum field effect mobility of 0.63 cm²/V s, operating at − 1 V with an on/off current ratio of ~ 10³.     

Physical properties of very thin SnS films deposited by thermal evaporation

SnS films with thicknesses of 20-65 nm have been deposited on glass substrates by thermal evaporation. The physical properties of the films were investigated using X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and ultraviolet-visible-near infrared spectroscopy at room temperature. The results from XRD, XPS and Raman spectroscopy analyses indicate that the deposited films mainly exhibit SnS phase, but they may contain a tiny amount of Sn₂S₃. The deposited SnS films are pinhole free, smooth and strongly adherent to the surfaces of the substrates. The color of the SnS films changes from pale yellow to brown with the increase of the film thickness from 20 nm to 65 nm. The very smooth surfaces of the thin films result in their high reflectance. The direct bandgap of the films is between 2.15 eV and 2.28 eV which is much larger than 1.3 eV of bulk SnS, this is deserving to be investigated further.     

真空热沉积过程中有机薄膜生长的模拟研究

利用Monte Carlo方法对真空蒸发系统下的有机薄膜生长过程进行了模拟.在该系统模型中,Ns个点蒸发源均匀分布在半径为R的圆周上,基板相对蒸发源所在平面距离为d.利用该模型分析了膜厚分布以及点蒸发源个数Ns、蒸发源与基板的相对位置R和d对薄膜厚度均匀性的影响,并通过实验对仿真结果进行了验证.结果显示,增加蒸发源个数、增大相对基板位置均可以有效提高薄膜的均匀性,测试发现薄膜样品的精度MaX-Min均保持在5%左右.     

Influence of annealing on characteristics of tin disulfide thin films by vacuum thermal evaporation

In this paper, we reported on an approach to prepare tin disulfide (SnS₂) thin films on soda-lime glass substrates by vacuum thermal evaporation using SnS₂ powders as a source. The influence of annealing on the chemical composition, crystal structure, surface morphology, and optical band gap of the SnS₂ thin films was systemically investigated. The as-grown SnS₂ thin film was amorphous, homogeneous, smooth, nearly stoichiometric, with no pinhole and crack free, and with an optical band gap of 2.41 eV. After the SnS₂ thin film was annealed at 300 °C, the crystallization of SnS₂ was demonstrated by X-ray diffraction and scanning electron microscope with a characteristic of a preferred orientation along (001) plane with hexagonal phase and the sheet appearance of the SnS₂ crystals. At the annealing temperature of 350 °C, some SnS₂ crystallites and a few pinholes appeared on the surface of the SnS₂ thin films, though the SnS₂ thin film was not oxidized. When the annealing temperature was increased to 400 °C, SnS₂ was gradually oxidized into an approximate spherical shape of SnO₂ from the top to the bottom of the SnS₂ thin film by trace O₂ in the furnace. Therefore, our experiment suggested that the annealing temperature of the SnS₂ thin film using the vacuum thermal evaporation should not be over 300 °C as a window layer in compound thin film solar cells.     

薄膜低温热膨胀系数测量方法研究

热膨胀系数是材料在低温应用中最重要的力参数之一,薄膜材料的许多性质与其同种块材差别较大.针对预应力大小对测试结果的可能影响,提出了两种薄膜低温热膨胀系数的测量方法,直接测量法和间接测量法.测试温度范围为室温至77 K,可以进行施加不同预应力和在更低温度下进行测量.     

薄膜生长的三维蒙特卡罗模型

构造三维蒙特卡罗模型,研究了六边形基底薄膜生长的过程.在模型中针对每个原子考虑了原子沉积、原子扩散及原子脱附三个动力学过程,并认为这三个过程是相互独立的,即在同一计算步长中三个过程依据各自的概率发生.经过生长过程可视化的结果表明,薄膜原子之间的相互作用能、基底温度和沉积速率对薄膜的生长方式有显著的影响.这一结论得到了实验的验证.     

一种具有电双稳特性的聚合物薄膜

发现了在室温下具有电双稳特性的聚合物材料聚对萘二甲酸乙二酯(PEN)。通过真空蒸发方法制备的PEN薄膜,其表面晶粒尺寸小于100nm,粗糙度也为纳米量级,而且具有较高的热稳定性。在3．5V电压作用下,PEN薄膜可从高阻状态跃变到低阻状态,跃迁时间小于20ns。该材料有可能用于大容量存储器的制作。     

Enhanced conductivity in iodine doped polyaniline thin film formed by thermal evaporation

Thermal evaporation technique was employed to deposit pristine and iodine doped polyaniline (PANI) thin films on glass substrates. PANI was synthesized by the chemical oxidation method. Iodine doping was carried out by evaporation. The polymer synthesized was characterized by Thermo Gravimetric Analysis (TGA), Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-VIS) spectroscopy. The evaporation temperature was optimized from TGA measurements. The thin film was deposited in vacuum at 1.33 × 10^− 4 Pa by thermal evaporation of PANI. The polymer film was characterized by FTIR and UV-VIS spectroscopy. The surface morphology of the films was studied by field emission scanning electron microscopy. The resistivity was measured by van der Pauw technique. The conductivity of the doped films was seen to increase with the iodine concentration and many fold increase in conductivity was observed in comparison to the pristine films. The increase in conductivity is due to the generation of polaron band in the band gap upon iodine doping.     

New possibility on InZnO nano thin film for green emissive optoelectronic devices

Indium zinc oxide (InZnO) nano thin film was prepared from InZnO nanoparticles (NPs) by thermal evaporation technique. Fourier transform infrared spectroscopy showed the presence of metal-oxide bond. X-ray diffraction pattern revealed the mixed phase structure. The presence of elements In, Zn and O were identified from energy dispersive X-ray analysis. Size of the NPs was found to be 171 and 263 nm by transmission electron microscopy. Scanning electron microscopy image showed the spherical shape uniform morphology with uniform distribution grains. Photoluminescence spectrum exhibited a broad green emission for InZnO nano thin film. The acquired results of structure, smooth morphology and photoluminescence property suggested that the InZnO nano thin film to be a promising material for room temperature green emissive optoelectronic, laser diodes, solar cells and other optical devices.     

薄膜材料导热行为及其测试和预测

薄膜材料在集成电路,光电子技术,微结构传感器等微电子元件的应用日益广泛,其导热性能直接影响元器件的热噪声,进而对其可行一和使用性能产生明显影响,薄膜材料导热性能及其测试研究愈益受人瞩目,为此,本文对薄膜材料导热性能及各种测试方法进行了综述,并在分析薄膜微结构模型的基础上,对计算薄膜有效热导率的不同预测议程进行了评述,从而可为薄膜材料的制备工艺和性能变化提供技术判据。     

Fabrication of a novel organic polymer thin film

Fabrication of organic polymer thin films and organic semiconductors are critical for the development of sophisticated organic thin film based devices. Radio Frequency plasma polymerisation is a well developed and widely used fabrication technique for polymer thin films. This paper describes the fabrication of an organic polymer thin film from a monomer based on Lavandula angustifolia. Several polymer thin films were manufactured with thicknesses ranging from 200 nm to 2400 nm. The energy gap of the polymer thin film was measured to be 2.93 eV. The refractive index and extinction coefficient was determined to be 1.565 (at 500 nm) and 0.01 (at 500 nm) respectively. The organic polymer thin film demonstrates the possibility of an environmentally friendly, cost effective organic semiconductor.