In situ monitoring of the growth of Cu(In,Ga)Se2 thin films

Thin films of Cu(In,Ga)Se₂ were grown by co-evaporation process in a conventional vacuum coating system at the base pressure of 10⁻⁵ mbar. The controllable of the two-stage growth process was developed. During the growth process, substrate temperature, graphite heater temperature, heating output power and temperature of the CIGS surface were monitored simultaneously. In this setup, we use the change in the thermal behavior of the substrate due to the variations in emissivity of CIGS film during the transition of Cu-rich to Cu-poor in the second stage corresponding to the change of power fed into the substrate heater as the control signal. By observing the variation of control signals, the desired final composition of the film can be obtained. Using our device fabrication, Al/ZnO(Al)/CdS/CIGS/Mo/SLG solar cells with efficiency over 14% (without AR) were achieved.     

对GaN薄膜不同腐蚀方法的腐蚀坑的研究

用Thomas Swan公司的MOCVD系统在蓝宝石(0001)面上生长了高质量的GaN薄膜.采用多种化学腐蚀方法,如熔融KOH,H3PO4与H2SO4混合酸和HCl气相腐蚀法,利用SEM及TEM技术对GaN薄膜中的位错进行了研究.SEM显示在GaN薄膜相同位置处,不同腐蚀法所得的腐蚀坑的形态和密度有明显差别.结果表明HCl气相腐蚀可以显示纯螺位错、纯刃位错和混合位错;H3PO4与H2SO4混合酸腐蚀可以显示纯螺位错和混合位错;而熔融KOH腐蚀仅能显示纯螺位错.     

Ф100mm掺硫InP单晶生长研究

InP以其众多的优越特性使之在许多高技术领域有广泛应用.掺硫n型InP材料用于激光器、LED、光放大器、光纤通信等光电领域.为了降低成本和适应新型器件制造的要求,本文进行了直径100mm掺硫InP单晶生长和性质研究.首先解决了大容量直接合成技术,其次解决了大直径单晶生长的关键技术,保证了一定的成晶率.采用降低温度梯度等措施,降低位错密度,提高晶体完整性.制备出100mm掺硫InP整锭〈100〉InP单晶和单晶片.经过测试其平均EPD小于5×104cm-2,载流子浓度大于3×1018cm-3.本文还对影响材料成晶的放肩角进行了研究,一般生长大直径单晶采用大于70.或平放肩技术都可以有效地避免孪晶的产生.     

淫羊藿苷含量对Mg/UMAO/CS/IC涂层性能的影响

为了研究淫羊藿苷含量对镁/超声微弧氧化/壳聚糖/淫羊藿苷（Mg/UMAO/CS/IC）涂层性能的影响,并提高纯镁的耐蚀性,采用电泳沉积（EPD）和UMAO技术在纯镁基体上制备Mg/UMAO/CS/IC涂层。采用扫描电子显微镜（SEM）、X射线衍射（XRD）、原子力显微镜（AFM）和傅立叶变换红外光谱（FTIR）对涂层的特征进行分析。对不同样品在模拟体液中进行了电化学阻抗和动电位极化的腐蚀行为研究。结果表明：当IC含量为0.4 g/L时CS/IC层具有较好的封孔效果。添加不同IC含量的Mg/UMAO/CS/IC涂层均由Mg、MgO、CS和Mg₂SiO₄组成。不同IC含量涂层的自腐蚀电流密度（i_corr）比Mg至少都低一个数量级,能为镁基底提供更有效的保护。IC含量为0.4 g/L时Mg/UMAO/CS/IC涂层的耐蚀性更好,自腐蚀电流密度（1.667×10^-6 A/cm²）最小。Mg/UMAO/CS/IC涂层可有效解决纯镁在临床骨内固定应用上降解过快的问题。     

Effect of suspension medium on the electrophoretic deposition of hydroxyapatite nanoparticles and properties of obtained coatings

The suspensions of hydroxyapatite (HA) nanoparticles were prepared in different alcohols. The zeta potential of HA nanoparticles was the highest in butanolic suspension (65.65 mV) due to the higher adsorption of RCH₂OH₂⁺ species via hydrogen bonding with surface P3OH group of HA. Electrophoretic deposition was performed at 20 and 60 V/cm for different times. Deposition rate was faster in low molecular weight alcohols due to the higher electrophoretic mobility of HA nanoparticles in them. The coating deposited from butanolic suspension had the highest adhesion strength and corrosion resistance in SBF solution at 37.5 °C. The surface of this coating was covered by apatite after immersion in SBF solution for 1 week.     

Effects of Al interlayer coating and thermal treatment on electron emission characteristics of carbon nanotubes deposited by electrophoretic method

The effects of aluminum (Al) interlayer coating and thermal post-treatment on the electron emission characteristics of carbon nanotubes (CNTs) were investigated. These CNTs were deposited on conical-shaped tungsten (W) substrates using an electrophoretic method. The Al interlayers were coated on the W substrates via magnetron sputtering prior to the deposition of CNTs. Compared with the as-deposited CNTs, the thermally treated CNTs revealed significantly improved electron emission characteristics, such as the decrease of turn-on electric fields and the increase of emission currents. The observations of Raman spectra confirmed that the improved emission characteristics of the thermally treated CNTs were ascribed to their enhanced crystal qualities. The coating of Al interlayers played a role in enhancing the long-term emission stabilities of the CNTs. The thermally treated CNTs with Al interlayers sustained stable emission currents without any significant degradation even after continuous operation of 20 h. The X-ray photoelectron spectroscopy (XPS) study suggested that the cohesive forces between the CNTs and the underlying substrates were strengthened by the coating of Al interlayers.     

Electrophoretic deposition of ethanol steam-reforming catalysts on metal plates for the development of catalytic-wall reactors

A procedure based on electrophoretic deposition (EPD) was developed to coat metal plates with powder catalysts. The method was tested on stainless-steel plates with three Ni-based catalysts for the steam reforming of ethanol. The catalysts (Ni/La₂O₃/γ-Al₂O₃) contained 15% Ni and 8% La, and were prepared using three types of γ-alumina with different textural properties. The powder catalysts were suspended in isopropanol, and EPD deposition was performed with a voltage of 100 V and a distance between electrodes of 2 cm. Deposition time was varied between 3 and 7 min, which gave a thickness of the catalyst layer from around 30 to 100 μm. The morphology of the catalyst layer was dependent on the textural characteristics of the γ-Al₂O₃ used to prepare the catalyst. The activity of the catalyst plates was tested at 773 K using a steam to carbon molar ratio of 4. Significant differences in the selectivity towards ethanol dehydrogenation, reforming, and dehydration to ethylene could be observed between the three catalysts. Carbon deposition on the surface of the plates could be easily determined by SEM/ESEM.     

Fabrication of Titanate Barium Films by Electrophoretic Deposition Technique

EPD （electrophoretic deposition） technique has been shown as an effective method to produce thin ore thick layers at voltage 5-100 V onto Ni conductive substrate. The aim of this study is to use the EPD method to fabricate films from suspensions BaTiO3. The effects of the EPD process parameters such as the suspension concentration, deposition time, electrical field strength on the specific EPD deposited weight, morphology particles were used. The surface microstructures of the as-deposited films were investigated by SEM （scanning electron microscopy）. A homogeneous microstructure was obtained at applied electric field of 100 V and I min of deposition time at an electrode distance of 1.0 cm.     

Dislocation profiles in HgCdTe(100) on GaAs(100) grown by metalorganic chemical vapor deposition

We studied dislocation etch pit density (EPD) profiles in HgCdTe(lOO) layers grown on GaAs(lOO) by metalorganic chemical vapor deposition. Dislocation profiles in HgCdTe(lll)B and HgCdTe(lOO) layers differ as follows: Misfit dislocations in HgCdTe(lll)B layers are concentrated near the HgCdTe/CdTe interfaces because of slip planes parallel to the interfaces. Away from the HgCdTe/CdTe interface, the HgCdTe(111)B dislocation density remains almost constant. In HgCdTe(lOO) layers, however, the dislocations propagate monotonically to the surface and the dislocation density decreases gradually as dislocations are incorporated with increasing HgCdTe(lOO) layer thicknesses. The dislocation reduction was small in HgCdTe(lOO) layers more than 10 μm from the HgCdTe/CdTe interface. The CdTe(lOO) buffer thickness and dislocation density were similarly related. Since dislocations glide to accommodate the lattice distortion and this movement increases the probability of dislocation incorporation, incorporation proceeds in limited regions from each interface where the lattice distortion and strain are sufficient. We obtained the minimum EPD in HgCdTe(100) of 1 to 3 x 10⁶ cm^-2 by growing both the epitaxial layers more than 8 μm thick.     

电泳沉积法制备Ba0.6Sr0.4TiO3厚膜及其电学性能研究

采用电泳沉积法在Pt/Ti/SiO2/Si基底上制备了厚度为33μm的Ba0.6Sr0.4TiO3(BST40)厚膜,研究了其介电调谐特性、漏电流特性和铁电特性.实验结果表明:采用水热法制备纳米BST40粒子,经250MPa高压压制,950°C热处理后,BST40厚膜可形成完整的立方钙钛矿结构且表面致密、无裂纹. ε-V特性表明,1kHz时厚膜调谐率可达59.2%.Ⅰ-Ⅴ特性表明,当电压从-25～25V变化时,漏导电流100μA/cm2.测量了在1kHz,不同温度下厚膜的电滞回线.在0°C时,其剩余极化强度为1.06μC/cm2.