楔形Al薄膜的物理特性

采用真空蒸镀方法,利用液体衬底在沉积过程中的扩散,形成了沉积在玻璃表面的楔形铝薄膜,并研究了它的结构和I-V特性.实验表明,楔形铝薄膜的斜率仅10^-6—10^-7,具有与一般非平整薄膜不同的I-V特性,其非平整效应不能用普通的非平整薄膜的RRN理论模型来解释. 关键词： 楔形铝薄膜     

热丝化学气相沉积技术低温制备多晶硅薄膜的结构与光电特性

以金属W和Ta为热丝，采用热丝化学气相沉积 ，在250℃玻璃衬底上沉积多晶硅薄膜.研究了热丝温度、沉积气压、热丝与衬底间距等沉积参数对硅薄膜结构和光电特性的影响，在优化条件下获得晶态比X_c＞90%，暗电导率σ_d=10^-7—10-6Ω ^-1cm^-1，激活能E_a=0.5eV，光能隙E_opt≤1.3 eV的多晶硅薄膜. 关键词： 多晶硅薄膜 热丝化学气相沉积 光电特性     

楔形金薄膜系统中的反常跳跃电导和隧道效应

采用真空蒸镀方法，利用液体衬底在沉积过程中的线性扩散过程，在玻璃表面制备出斜率仅为10^-5的楔形金薄膜逾渗系统，并用四引线方法测量了从该薄膜系统中得到的均匀无序金薄膜的导电特性.实验结果表明：和通常的平整薄膜逾渗系统相比，该薄膜系统呈现更为强烈的跳跃电导和隧道效应. 关键词： 带状薄膜 跳跃电导 隧道效应     

碲化铋红外透明导电薄膜的制备与光电性能（特邀）

采用射频磁控溅射法在石英衬底和硒化锌衬底上制备了碲化铋薄膜,分别研究了薄膜厚度、退火温度对薄膜微观结构和光电性能的影响。利用X射线衍射仪、X射线光电子能谱仪和冷场发射扫描电子显微镜,分析了薄膜结构、成分和形貌。结果表明,退火有利于薄膜的结晶,且不改变晶体的择优取向。傅里叶变换红外光谱测试结果表明,在石英衬底和硒化锌衬底上沉积的薄膜,光学透过率随着薄膜厚度和退火温度的增加而减小,在硒化锌衬底上沉积的薄膜透过波段比石英长,且光学透过率更加稳定。霍尔效应测试结果表明,随着薄膜厚度和退火温度的增加,薄膜的电阻率逐渐减小,最小为1.448×10^-3Ω·cm,迁移率为27.400 cm²·V^-1·s^-1,载流子浓度为1.573×10²⁰ cm^-3。在石英衬底上沉积的15 nm厚的Bi₂Te₃薄膜,在1～5μm波段的透过率达到80%,退火200℃后透过率达到60%,电阻率为5.663×10^-3Ω·cm。在...     

非化学计量比靶材溅射制备Cu-Al-O薄膜的光学电学性质研究

考虑到铜铝溅射速率的差别,使用铜铝比例为0.9 ∶1的多晶CuAlO₂靶材,用射频磁控溅射法制备Cu-Al-O薄膜.研究不同衬底温度对薄膜光学电学性能的影响.在衬底温度500 ℃附近,薄膜在可见光范围内具有很好的透光性,达到70%,计算拟合得到直接帯隙为3.52 eV,与CuAlO₂相的理论值符合较好.在室温附近,薄膜导电符合半导体热激活机理,在衬底温度为500 ℃附近薄膜电导率达到2.48×10^-3 S·cm^-1. 关键词： Cu-Al-O 衬底温度 透过率 电导率     

衬底温度对反应磁控溅射W掺杂ZnO薄膜的微观结构及光电性能的影响

采用直流脉冲反应磁控溅射方法生长W掺杂ZnO（WZO）透明导电氧化物薄膜并研究了衬底温度对薄膜微观结构、组分、表面形貌以及光电性能的影响.实验结果表明,WZO薄膜具有良好的（002）晶面择优取向,且适当的衬底温度是制备优质WZO薄膜的关键因素.随着衬底温度升高,薄膜表面粗糙度先增大后减小;衬底温度较高时,薄膜的结构致密,结晶质量好,电子迁移率高.当衬底温度为325℃时,WZO薄膜获得最低电阻率9.25×10^-3Ω·cm,方块电阻为56.24Ω/□,迁移率为11.8 cm² V^-1·s^-1,其在可见光及近红外区域（400—1500 nm）范围的平均透过率达到85.7%.     

面向微通道换热器的耐久性超疏水涂层调控及其抑霜性能

本研究针对微通道换热器提出了一种具有良好耐久性的超疏水涂层制备方法。首先采用一步水热法原位合成具有微纳二级粗糙结构的锌铝水滑石(Zn-Al LDH),再通过电化学沉积法在表面沉积低表面能物质。水热法制备的粗糙结构很好的保护了电化学沉积得到的低表面能薄膜,增强了超疏水涂层的耐久性。同时,电化学测试发现,基体的自腐蚀电位从-1.454 V正移至-1.2989 V,腐蚀电流密度从纯铝微通道表面的2.564×10^-3A·cm^-2降低到5.2×10^-6A·cm^-2,显示出超疏水微通道换热器具有极好的耐腐蚀性能。此外,超疏水微通道的结霜实验和模拟结果表明其具有良好的抗结霜性能。     

生长条件对脉冲激光沉积制备ZnO：Al薄膜光电性能的影响

本文研究了脉冲激光沉积(PLD)生长过程中, 铝掺量、氧压及衬底温度等实验参数对ZnO:Al(AZO)薄膜生长的影响, 并利用扫描电子显微镜、原子力显微镜、X射线衍射、霍尔效应、光透射光谱等实验手段对其透明导电性能进行了探讨. 变温霍尔效应和光透射测量表明, 当靶材中铝掺量大于0.5 wt%时, 所制备AZO薄膜中铝施主在80 K时已完全电离, 因Bernstein-Moss (BM) 效应其带隙变大, 均为重掺杂简并半导体. 进一步系统研究了氧压和衬底温度对AZO薄膜透明导电性能的影响, 实验发现当氧压为1 Pa, 衬底温度为200 ℃时, AZO 导电性能最好, 其霍尔迁移率为28.8 cm²/V·s, 薄膜电阻率最小可达2.7×10^-4 Ω·cm, 且在可见光范围内光透过率超过了85%. 氧压和温度的增加, 都会导致薄膜电阻率变大. 关键词： 脉冲激光沉积法 ZnO：Al薄膜 透光性 导电性     

金原子在熔融玻璃表面的凝聚特性

研究了沉积在熔融玻璃表面的金原子的扩散、凝聚以及结晶行为.实验结果表明:金原子在胶状的玻璃表面先形成具有特征结构的网状薄膜,其中金原子晶粒直径约为20nm;然后网孔逐渐增大直至薄膜破裂,金原子凝聚成准圆形的团族,其饱和直径约为1.2μm,扩散系数为10^-7—10^-8cm²/s数量级;通过快速且准无规地扩散,准圆形团簇最终凝聚成直径约为50μm的大型分枝状凝聚体 关键词： 薄膜 凝聚 扩散     

金属Fe薄膜的PLD制备及其非线性光学性质研究

采用脉冲激光沉积（PLD）技术在MgO基片上制备了金属Fe薄膜.利用原子力显微镜研究了不同制备温度对薄膜表面形貌的影响.x射线衍射分析表明沉积温度大于500℃时，Fe薄膜在MgO基片上有很好的结晶性，并有单一取向.通过z扫描方法测量了超薄Fe膜的光学非线性，得到了Fe薄膜的非线性折射率n₂＝709×10^-5cm²/ kW，非线性吸收系数 β＝-552×10^-3cm/W. 关键词： Fe薄膜 非线性 脉冲激光沉积     

Formation of ultrasmall germanium nanoislands with a high density on an atomically clean surface of silicon oxide

The experimental results of an investigation into the initial stages of growth of a germanium film on an atomically clean oxidized silicon surface are reported. It is shown that the growth of the germanium film in this system occurs through the Volmer-Weber mechanism. Elastically strained nanoislands with a lateral size of less than 10 nm and a density of 2 × 10¹² cm^?2 are formed on the oxidized silicon surface. In germanium films with a thickness greater than 5 monolayers (ML), there also arise completely relaxed germanium nanoislands with a lateral size of up to 200 nm and a density of 1.5 × 10⁹ cm^?2.     

AFM Study on the Formation Mechanism and Microstructure of Ni Atomic Aggregates on Liquid Substrates

We study the formation mechanism and microstructure of nickel （Ni） atomic aggregates on the silicone oil surfaces by atomic force microscopy （AFM）. Initially, the deposited atoms nucleate and form the compact clusters on the liquid surfaces. Then they perform Brownian motion and adhere upon impact. Finally the branched aggregates are formed. The Ni aggregates exhibit granular structure. The mean size of the granularities in the aggregates is of the order of 10 nm and it decreases with the nominal film thickness. The experiment shows that the Ni aggregates perform a directional diffusion towards the sample edge. The interpretation for this phenomenon is presented.     

Transparent conductive ZnO:Al films grown by atomic layer deposition for Si-wire-based solar cells

Structural, electrical, and optical properties of atomic layer-controlled Al-doped ZnO (ZnO:Al) films grown by atomic layer deposition (ALD) on glass substrates were characterized at various growth temperatures for use as transparent electrodes. The Al atomic content in ZnO:Al films increased due to the reduced ZnO film growth rate with increasing temperature. The preferred orientation of ZnO:Al films was changed, and the optimum condition for best crystallinity was identified by varying the growth temperature. Furthermore, the carrier concentration of free electron was increased by substituting the Zn sites with Al atoms in the crystal, resulting from monolayer growth based on alternate self-limiting surface chemical reactions. The electrical resistivity of ZnO:Al film grown by ALD at 225 °C reached the lowest value of 8.45 × 10⁻⁴ Ω cm, with a carrier mobility of 9.00 cm² V⁻¹ s⁻¹ and optical transmittance of ∼93%. This result demonstrates that ZnO:Al films grown by ALD possess excellent potential for applications in electronic devices and displays as transparent electrodes and surface passivation layers.     

硅油基底表面铁薄膜的生长机理及表面有序结构

利用直流溅射方法在液体基底(硅油)表面成功制备出金属铁薄膜系统，研究了其生长机理及特征的表面有序结构.实验发现铁薄膜的生长过程与液相基底表面非磁性金属薄膜的情况类似，基本服从二阶段生长模型.连续铁薄膜中可观测到尺寸巨大的圆盘形有序结构，其生长演化与溅射功率、沉积时间和真空环境中的生长时间等实验条件密切相关.实验证明，此类有序结构是在薄膜内应力作用下，铁原子及原子团簇在液体表面自由扩散迁移，并最终在硅油基底表面某些区域成核凝聚所致.在较大溅射功率和沉积时间条件下，圆盘外部区域的铁薄膜中形成周期分布的波纹褶皱，其波长约为10 μm，波峰基本与圆盘的边界平行.进一步研究表明：在沉积过程中，由于沉积铁原子的局域能量作用，导致硅油的表面层结构发生改变而形成一聚合物层；在随后的冷却过程中，聚合物层的强烈收缩使铁薄膜处于很大的压应力场中，促使薄膜起皱形成波纹结构. 关键词： 液体基底 铁薄膜 生长机理 有序结构     

Molecular dynamics and experimental studies on deposition mechanisms of ion beam sputtering

Molecular dynamics (MD) simulation and experimental methods are used to study the deposition mechanism of ionic beam sputtering (IBS), including the effects of incident energy, incident angle and deposition temperature on the growth process of nickel nanofilms. According to the simulation, the results showed that increasing the temperature of substrate decreases the surface roughness, average grain size and density. Increasing the incident angle increases the surface roughness and the average grain size of thin film, while decreasing its density. In addition, increasing the incident energy decreases the surface roughness and the average grain size of thin film, while increasing its density. For the cases of simulation, with the substrate temperature of 500 K, normal incident angle and 14.6 × 10⁻¹⁷ J are appropriate, in order to obtain a smoother surface, a small grain size and a higher density of thin film. From the experimental results, the surface roughness of thin film deposited on the substrates of Si(1 0 0) and indium tin oxide (ITO) decreases with the increasing sputtering power, while the thickness of thin film shows an approximately linear increase with the increase of sputtering power.     

Simultaneous interaction of methyl radicals and atomic hydrogen with amorphous hydrogenated carbon films, as investigated with optical in situ diagnostics

Methyl radicals (CH₃) and atomic hydrogen (H) are dominant radicals in low-temperature plasmas from methane. The surface reactions of these radicals are believed to be key steps leading to deposition of amorphous hydrogenated carbon (a-C:H) films or polycrystalline diamond in these discharges. The underlying growth mechanism is studied, by exposing an a-C:H film to quantified radical beams of H and CH₃. The deposition or etching rate is monitored via ellipsometry and the variation of the stoichiometry is monitored via isotope labeling and infrared spectroscopy. It was shown recently that, at 320 K, methyl radicals have a sticking coefficient of 10^-4 on a-C:H films, which rises to 10^-2 if an additional flux of atomic hydrogen is present. This represents a synergistic growth mechanism between H and CH₃. From the interpretation of the infrared data, a reaction scheme for this type of film growth is developed: atomic hydrogen creates dangling bonds by abstraction of bonded hydrogen within a surface layer corresponding to the range of H in a-C:H films. These dangling bonds serve at the physical surface as adsorption sites for incoming methyl radicals and beneath the surface as radicalic centers for polymerization reactions leading to carbon–carbon bonds and to the formation of a dense a-C:H film. Received: 18 July 2000 / Accepted: 12 December 2000 / Published online: 3 April 2001     

The conversion of wettability in transparent conducting Al-doped ZnO thin film

We report on the systematic changes of surface wettability in one of the most promising transparent conducting oxide materials, Al-doped ZnO (AZO) thin films. It was revealed that the characteristic surface wettability, which would make a key role in adhesion with other layers of optoelectronic device, can be largely changed by Al concentrations and film growth temperature. Keeping the electrical conductivity constant, the water contact angle (WCA) of a 2 mol% AZO film was changed by about 50 ^°C depending on the surface roughness. In the samples grown at 300 ^°C, the roughness enhancement was large and a hydrophobic surface formed, whereas in the samples grown at 500 ^°C a hydrophilic surface formed. We attributed the variation in surface wettability with growth temperature to changes in surface morphology. This result suggests that 2 mol% Al doping concentration can be considered as a critical concentration in changing of surface morphology of AZO as well as in electrical properties.     

Thickness dependence of the surface plasmon dispersion in ultrathin aluminum films on silicon

The collective excitation in Al films deposited on Si(1 1 1)-7 × 7 surface was investigated by high-resolution electron-energy-loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). At the Al film thickness d < 10 ML, the surface plasmon of Al film has only a small contribution to the observed energy-loss peaks in the long wavelength limit (q_∥≈0), while its contribution becomes significant for q_∥>d^-1. More interestingly, for thin Al films, the initial slope of the surface plasmon dispersion curve is positive at q_∥∼0, in a sharp contrast to bulk Al surface where the energy dispersion is negative. These observations may be explained based on the screening interaction of the space charge region at the Al-Si interface.