铜膜碘化法制备p型CuI薄膜及其用作空穴传输层的反型钙钛矿电池性能

γ相碘化亚铜(γ-CuI)是一种带隙为3.1 eV的p型半导体材料, 适合应用于发光二极管和太阳能电池等光电子器件。本研究利用简单的铜膜碘化法制备了CuI薄膜, 探究了碘化时间、温度及铜/碘比等生长条件对其透明导电性能的影响。在最优碘化时间(30 min)和碘化温度(120℃)下, 制备出了高透过率(可见光范围>75%)、导电性能好(电阻率4.4×10^-2 Ω·cm)的CuI薄膜。利用CuI薄膜作为空穴传输层, 组装了CuI/CH₃NH₃PbI₃/PCBM反型平面钙钛矿电池, 获得的最高光电转换效率为8.35%, 讨论了CuI薄膜透明导电性能对钙钛矿电池光电转换效率的影响机理。     

固体氧化物燃料电池阳极的相转化流延制备和电化学性能研究

采用相转化流延一步制备了NiO-Zr_0.84Y_0.16O_2-δ (YSZ)阳极支撑层和功能层, 前者厚度为~700 μm, 含有沿厚度方向定向排列的开放直孔, 后者厚度为~60 μm。采用浆料涂膜法和高温共烧在阳极上制备厚度为15 μm的YSZ电解质薄膜, 丝网印刷制备YSZ-La_0.84Sr_0.16MnO_3-δ (LSM)(质量比50:50)阴极。所制备的单电池显示出较高的电输出性能。以H₂-3%H₂O为燃料和环境空气为氧化剂, 800 ℃时电池的峰功率密度达到891 mW/cm², 电池即使在高电流密度测试条件下也未出现明显的浓差极化, 这是由于其阳极具有开放直孔结构, 气相输运阻力小。     

氢气氛退火对硅上低温外延制备的硅锗薄膜性能的影响

采用反应型热化学气相沉积系统在硅(100)衬底上外延生长富锗硅锗薄膜。四氟化锗作为锗源, 乙硅烷作为还原性气体。通过设计表面反应, 在低温条件下(350℃)制备了高质量的富锗硅锗薄膜。研究了氢退火对低温硅锗外延薄膜微结构和电学性能的影响。结果发现退火温度高于700℃时, 外延薄膜的表面形貌随着退火温度的升高迅速恶化。当退火温度为650℃时, 获得了最佳的退火效果。在该退火条件下, 外延薄膜的螺旋位错密度从3.7×10⁶ cm^-2下降到4.3×10⁵ cm^-2, 表面粗糙度从1.27 nm下降到1.18 nm, 而外延薄膜的结晶质量也有效提高。霍尔效应测试表明, 经退火处理的样品载流子迁移率明显提高。这些结果表明, 经过氢退火处理后, 反应型热化学气相沉积制备的低温硅锗外延薄膜可以获得与高温下硅锗外延薄膜相比拟的性能。     

n型SnS热电材料的制备与性能研究

SnS由低毒、廉价、高丰度的元素组成, 在热电研究领域受到广泛关注。采用机械合金化(MA)结合放电等离子烧结(SPS)工艺制备了n型SnS_1-xCl_x(x=0, 0.02, 0.03, 0.04, 0.05, 0.06)多晶块体热电样品, 并研究了Cl^-掺杂量对SnS物相、微观结构以及电热输运性能的影响。结果表明: Cl^-的引入会提高电子浓度, 使SnS由本征p型转变为n型半导体。随着Cl^-掺杂量的增加, n型SnS半导体室温下的霍尔载流子浓度从6.31×10¹⁴ cm^-3 (x=0.03)增加到7.27×10¹⁵cm^-3 (x=0.06)。x=0.05样品在823 K取得最大的电导率为408 S·m^-1, 同时具有较高的泽贝克系数为-553 μV•K^-1, 使其获得最大功率因子为1.2 μW·cm^-1·K^-2。Cl^-的掺入会引入点缺陷, 散射声子, 使晶格热导率κ_lat由0.67 W·m^-1·K^-1(x=0)降至0.5 W·m^-1·K^-1 (x=0.02)。x=0.04样品在823 K获得了最大ZT为0.17, 相比于x=0样品(ZT~0.1)提高了70%。     

Sc2W3O12薄膜制备及其负热膨胀性能

采用脉冲激光沉积法制备了斜方相Sc₂W₃O₁₂薄膜。利用X射线衍射仪(XRD)和场发射扫描电镜(FESEM)对Sc₂W₃O₁₂靶材和Sc₂W₃O₁₂薄膜组分、表面形貌和靶材断面形貌进行表征, 研究衬底温度与氧分压对薄膜制备的影响。采用变温XRD和热机械分析仪(TMA)分析了Sc₂W₃O₁₂陶瓷靶材和薄膜的负热膨胀特性。实验结果表明: 经1000℃烧结6 h得到结构致密的斜方相Sc₂W₃O₁₂陶瓷靶材, 其在室温到600℃的温度范围内平均热膨胀系数为-5.28×10^-6 K^-1。在室温到500℃衬底温度范围内脉冲激光沉积制备的Sc₂W₃O₁₂薄膜均为非晶态, 随着衬底温度的升高, 薄膜表面光滑程度提高; 随着沉积氧压强增大, 表面平整性变差。非晶膜经1000℃退火处理7 min后得到斜方相Sc₂W₃O₁₂多晶薄膜, 在室温到600℃温度区间内, Sc₂W₃O₁₂薄膜的平均热膨胀系数为-7.17×10^-6 K^-1。     

海藻酸钠离子凝胶法制备直通孔氧化铝多孔陶瓷

利用海藻酸钠的离子凝胶过程, 采用溶剂置换结合冷冻干燥的工艺, 成功制备了具有高度有序六方排列的直通孔多孔氧化铝陶瓷, 整个工艺过程及所使用的原料都是环境友好的。研究结果表明, 1500℃烧结2 h样品的孔径尺寸在200 μm左右, 且与固相含量的关系不大, 而孔壁上存在0.3 μm~0.5 μm的小孔。通过控制浆料中氧化铝的固相含量可以对材料的性能进行有效地调控, 研究表明, 随着固相含量从5wt%提高到15wt%, 材料的密度从0.87 g/cm³提高到1.16 g/cm³, 渗透率从2.57×10^-11 m²下降到2.16×10^-11 m², 而抗压强度从(18.9±3.2) MPa提高到(44.2±5.4) MPa, 平行孔道方向的热导率从2.1 W/(m·K)提高到3.1 W/(m·K), 而垂直孔道方向的热导率从1.3 W/(m•K)提高到1.7 W/(m·K), 并且平行孔道方向热导率的增加幅度要明显大于垂直孔道方向。     

L-精氨酸掺杂钙钛矿太阳电池性能研究

钙钛矿太阳电池以其优异的性能和发展潜力而成为新能源领域研究热点, 但仍然存在缺陷密度大、稳定性差等不足。本研究通过实验对比多种常见氨基酸的掺杂效果后, 将小分子有机物L-精氨酸引入钙钛矿前驱体溶液, 并通过二元两步法制备钙钛矿太阳电池。L-精氨酸掺杂提升了器件的光电性能, 光电效率由18.81%提升到21.86%。L-精氨酸通过降低钙钛矿层缺陷密度(由4.83×10¹⁶ cm^-3降低到3.45×10¹⁶ cm^-3), 减少了载流子非辐射复合, 延长了载流子的平均寿命, 且钙钛矿晶粒尺寸增大、晶界减少、薄膜吸光能力增强且稳定性提升, 迟滞效应得到抑制。这是由于L-精氨酸的多种基团与钙钛矿材料作用钝化了缺陷造成的。本研究为钙钛矿太阳电池的性能优化提供了一种借鉴方法。     

p型氧化镍薄膜晶体管的微流控法制备研究

可以图形化和沉积同时进行的镀膜技术可有效简化器件制备流程, 从而降低成本。本工作研究了一种新型的图形化沉积镀膜技术-微流控法: 将宽度及间隔均为80 μm、沟槽深度为2 μm左右的PDMS模板与衬底贴合构筑微流通道, 毛细力作用下前驱液可在微流通道内流动, 并在衬底表面形成图形化的液膜, 最后经热处理完成图行化的薄膜沉积。此外, 分析了硝酸镍/2-甲氧基乙醇前驱体的热分解过程和不同温度退火下前驱体粉末的相结构演化规律。最终利用微流控法图形化沉积技术制备了图形化的氧化镍沟道, 并构筑了薄膜晶体管器件。优化后的薄膜晶体管表现出典型的p型特征, 场效应迁移率可达0.8 cm²·V^-1·s^-1。     

Ge掺杂MnTe材料的热电输运性能

MnTe作为一种新型的无铅p型热电材料, 在中温区热电领域具有广阔的应用前景, 但其本身的热电性能不足以与高性能n型热电材料相匹配。本研究通过真空熔炼-淬火和放电等离子烧结的方法制备不同Ge掺杂量的致密且均匀的Mn_1.06-xGe_xTe(x=0, 0.01, 0.02, 0.03, 0.04)多晶块体样品。过量的Mn可以有效抑制MnTe₂相, 提高基体相的热电性能。通过掺杂4%Ge粉末, 材料的载流子浓度提高到7.328×10¹⁸ cm^-3, 电导率在873 K增大到7×10³ S∙cm^-1, 功率因子提升至620 μW∙m^-1∙K^-2。同时, 通过点缺陷增强声子散射使材料的热导率降低到0.62 W∙m^-1∙K^-1, 实现了对材料电声输运性能的有效调控。Mn_1.02Ge_0.04Te在873 K获得了0.86的热电优值ZT, 较纯MnTe材料提高了43%。     

溅射制备CdS薄膜及其在CdTe电池中的应用

采用射频磁控溅射方法分别在石英玻璃和TCO玻璃上制备了不同厚度的CdS薄膜,研究了CdS薄膜厚度对薄膜结构和光学性质的影响。在不同厚度的CdS/TCO衬底上,进一步制备成CdTe薄膜太阳电池。结果表明,CdS薄膜厚度的增加有利于薄膜的生长与结晶;110nm的薄膜具有禁带宽度为2.41eV的最大值;测试电池性能,得到CdS厚度为110nm的电池具有11.42%的最高转换效率。     

Structural, electrical, and optical studies on rapid thermally processed ferroelectric BaTiO3 thin films prepared by metallo-organic solution deposition technique

Polycrystalline BaTiO₃ thin films having the perovskite structure were successfully produced on platinum coated silicon, bare silicon, and fused quartz substrate by the combination of the metallo-organic solution deposition technique and post-deposition rapid thermal annealing treatment. The films exhibited good structural, electrical, and optical properties. The electrical measurements were conducted on metal-ferroelectric-metal (MFM) and metal-ferroelectric-semiconductor (MFS) capacitors. The typical measured small signal dielectric constant and dissipation factor at a frequency of 100 kHz were 255 and 0.025, respectively, and the remanent polarization and coercive field were 2.2 μC cm⁻² and 25 kV cm⁻¹, respectively. The resistivity was found to be in the range 10¹⁰–10¹² Ω·cm, up to an applied electric field of 100 kV cm⁻¹, for films annealed in the temperature range 550–700 °C. The films deposited on bare silicon substrates exhibited good film/substrate interface characteristics. The films deposited on fused quartz were highly transparent. An optical band gap of 3.5 eV and a refractive index of 2.05 (measured at 550 nm) was obtained for polycrystalline BaTiO₃ thin film on fused quartz substrate. The optical dispersion behavior of BaTiO₃ thin films was found to fit the Sellmeir dispersion formula well.     

A simple tool for quality evaluation of the microcrystalline silicon prepared at high growth rate

Silicon thin films were grown by plasma enhanced chemical vapor deposition at high-pressure (700 Pa), high-power (4– W/cm²) depletion regime using multi-hole cathode. Series of samples were deposited by varying hydrogen/silane ratio or plasma power to study evolution of film structure and transport properties near a-Si:H/μc-Si:H transition. We suggest a simple “μc-Si:H layer quality factor” based on the ratio of subgap optical absorption (1.4 eV)/ (1 eV) measured by constant photocurrent method. This ratio correlates well with the values of ambipolar diffusion lengths measured by surface photovoltage method perpendicularly to the substrate, i.e., in the direction of the collection of the photogenerated carriers in solar cells.     

PdSe2半导体薄膜的真空硒化法制备研究

PdSe₂薄膜主要通过机械剥离法和气相沉积法制得, 本研究采用一种简单有效的可在SiO₂/Si衬底上制备PdSe₂薄膜的方法。通过高真空磁控溅射技术在SiO₂/Si衬底上沉积一层Pd金属薄膜, 将Pd金属薄膜与Se粉封在高真空的石英管中并在一定的温度下进行硒化, 获得PdSe₂薄膜。根据截面高分辨透射电镜(HRTEM)照片可知PdSe₂薄膜的平均厚度约为30 nm。进一步研究硒化温度对PdSe₂薄膜电输运性能的影响, 当硒化温度为300 ℃时, 所制得的PdSe₂薄膜的体空穴浓度约为1×10¹⁸ cm^-3, 具有最大的室温迁移率和室温磁阻, 分别为48.5 cm²·V^-1·s^-1和12%(B=9 T)。值得注意的是, 本实验中通过真空硒化法获得的薄膜空穴迁移率大于通过机械剥离法制得的p型PdSe₂薄膜。随着硒化温度从300 ℃逐渐升高, 由于Se元素容易挥发, Pd薄膜的硒化程度逐渐减小, 导致薄膜硒含量、迁移率和磁电阻降低。本研究表明：真空硒化法是一种简单有效地制备PdSe₂薄膜的方法, 在贵金属硫族化合物的大面积制备及多功能电子器件的设计中具有潜在的应用价值。     

Microstructures of microcrystalline silicon thin films prepared by hot wire chemical vapor deposition

Undoped hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared at low temperature by hot wire chemical vapor deposition (HWCVD). Microstructures of the μc-Si:H films with different H₂/SiH₄ ratios and deposition pressures have been characterized by infrared spectroscopy X-ray diffraction (XRD), Raman scattering, Fourier transform (FTIR), cross-sectional transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The crystallization of silicon thin film was enhanced by hydrogen dilution and deposition pressure. The TEM result shows the columnar growth of μc-Si:H thin films. An initial microcrystalline Si layer on the glass substrate, instead of the amorphous layer commonly observed in plasma enhanced chemical vapor deposition (PECVD), was observed from TEM and backside incident Raman spectra. The SAXS data indicate an enhancement of the mass density of μc-Si:H films by hydrogen dilution. Finally, combining the FTIR data with the SAXS experiment suggests that the Si---H bonds in μc-Si:H and in polycrystalline Si thin films are located at the grain boundaries.     

Indium-doped ZnO thin films deposited by the sol–gel technique

Conducting and transparent indium-doped ZnO thin films were deposited on sodocalcic glass substrates by the sol–gel technique. Zinc acetate and indium chloride were used as precursor materials. The electrical resistivity, structure, morphology and optical transmittance of the films were analyzed as a function of the film thickness and the post-deposition annealing treatments in vacuum, oxygen or argon. The obtained films exhibited a (002) preferential growth in all the cases. Surface morphology studies showed that an increase in the films' thickness causes an increase in the grain size. Films with 0.18 μm thickness, prepared under optimal deposition conditions followed by an annealing treatment in vacuum showed electrical resistivity of 1.3 × 10^− 2 Ωcm and optical transmittance higher than 85%. These results make ZnO:In thin films an attractive material for transparent electrodes in thin film solar cells.     

Effect of deposition temperature on the structural and thermoelectric properties of bismuth telluride thin films grown by co-sputtering

Thermoelectric bismuth telluride thin films were prepared on SiO₂/Si substrates by radio-frequency (RF) magnetron sputtering. Co-sputtering method with Bi and Te targets was adopted to control films' composition. Bi_xTe_y thin films were elaborated at various deposition temperatures with fixed RF powers, which yielded the stoichiometric Bi₂Te₃ film deposition without intentional substrate heating. The effects of deposition temperature on surface morphology, crystallinity and electrical transport properties were investigated. Hexagonal crystallites were clearly visible at the surface of films deposited above 290 °C. Change of dominant phase from rhombohedral Bi₂Te₃ to hexagonal BiTe was confirmed with X-ray diffraction analyses. Seebeck coefficients of all samples have negative value, indicating the prepared Bi_xTe_y films are n-type conduction. Optimum of Seebeck coefficient and power factor were obtained at the deposition temperature of 225 °C (about − 55 μV/K and 3 × 10^− 4 W/K²·m, respectively). Deterioration of thermoelectric properties at higher temperature could be explained with Te deficiency and resultant BiTe phase evolution due to the evaporation of Te elements from the film surface.     

Fabrication of robust Bi3.25La0.75Ti3O12 thin film resistant to hydrogen damage

Ferroelectric bismuth lanthanum titanate (Bi_3.25La_0.75Ti₃O₁₂; BLT) thin films were deposited on Pt/TiO₂/SiO₂/Si substrate by chemical solution deposition method. The films were crystallized in the temperature range of 600–700 °C. The spontaneous polarization (P_s) and the switching polarization (2P_r) of BLT film annealed at 700 °C for 30 min were 22.6 μC/cm² and 29.1 μC/cm², respectively. Moreover, the BLT capacitor did not show any significant reduction of hysteresis for 90 min at 300 °C in the forming gas atmosphere.     

Depth profiling study of in situ CdCl2 treated CdTe/CdS heterostructure with glancing angle incidence X-ray diffraction

CdTe thin films have been deposited using spray pyrolysis technique without and with in situ CdCl₂ treatment. Scanning electron microscopy studies show enhanced grain growth in the presence of CdCl₂. Glancing angle incidence X-ray diffraction is used for the micro structural study of polycrystalline CdS/CdTe heterostructure at different depths by changing the incident angle. Spraying of CdCl₂ on CdS prior to CdTe deposition promotes S diffusion throughout CdTe film and also Te diffusion into CdS. Whereas spraying of CdCl₂ in between CdTe deposition prevents S diffusion partially and Te diffusion completely. There is an associated change in the microstress of the CdTe film at different layers. The films without CdCl₂ treatment show compressive microstress varying from −98 to −158 MPa with increasing incident angle. CdCl₂ spray during CdTe deposition shows compressive microstress, which varies from −98 MPa at the interface to −19 MPa near the surface and CdCl₂ spray prior to CdTe deposition leads to a mildly tensile stress, from +40 to +20 MPa, which is very close to the standard shear stress of 10 MPa for CdTe.