生长条件对GaAs/Si薄膜结构特性的影响

该文介绍以单晶Si为衬底,热壁外延制备适合作太阳电池的GaAs多晶薄膜.采用电子探针(EPMA)测定薄膜的组分、表面与剖面形貌,x射线衍射(XRD)分析生长薄膜的结构特性.并分析了各种工艺条件对GaAs薄膜结构特性的影响,得出制备表面呈绒面结构、晶粒为柱状结构、可用作廉价、高效GaAs太阳电池衬底的多晶薄膜材料的最佳生长条件源温为900℃,衬底温度为700℃,生长时间为3h.     

在导电玻璃衬底上热壁外延生长GaAs薄膜

该文报道以导电玻璃为衬底,采用热壁外延方法,制备GaAs多晶薄膜材料.采用电子探针(EPMA)测定薄膜的组分、表面与剖面形貌,x射线衍射(XRD)分析生长薄膜的结构,Raman散射(RSS)、光致发光光谱(PL)分析其光学性能.结果表明该薄膜性能良好、表面呈绒面结构、适合制作GaAs薄膜太阳电池.并全面分析了现有制备工艺条件对GaAs薄膜性能的影响,得出最佳的生长温度条件源温为900～930℃,衬底温度为500℃.     

Na掺入制备不锈钢衬底CIGS太阳电池

以轻质柔性不锈钢材料为衬底,利用共蒸发法制备较高质量的四元化合物Cu(In,Ga)Se2薄膜,在沉积CIGS薄膜前沉积一定厚度的NaF预置层,使得所制备的CIGS薄膜含有适量浓度的Na,并获得了10.06%的转换效率.利用X射线衍射仪和X射线荧光光谱仪分别测量了所制备薄膜的晶相和组分,利用扫描电子显微镜分析了不锈钢衬底CIGS太阳电池的断面形貌,最后分析了NaF的掺入对CIGS太阳电池的影响.     

用MOCVD方法制备ZnO：B透明导电薄膜及其性能优化

采用金属氧化物化学气相沉积(MOCVD)方法在石英衬底上生长氧化锌(ZnO)薄膜.改变薄膜材料的生长温度和掺杂气体硼烷(B2H6)的流速,制备一系列薄膜样品.通过x-射线衍射(XRD)、扫描电子显微镜(SEM)、透过率、反射率、电阻率和原子力显微镜(AFM)等测试分析,研究了材料生长温度和B2H6流速对薄膜生长速度、微观结构、薄膜晶向、光学透过率、光学禁带宽度、电阻率、表面粗糙度等特征参量的影响,经过优化实验条件,获得薄膜电阻率在10-3Ω·cm量级,可见光区域光学透过率在85%以上,成功制备低电阻率高光学透过率的ZnO透明导电薄膜.     

In2Se3薄膜生长及结晶择优取向的影响因素研究

(In,Ga)2Se3薄膜的生长结晶性的好坏直接影响着在其基础上化合生长的Cu(In,Ga)Se2(CIGS)薄膜以及CIGS太阳电池器件的性能.实验就多源共蒸发制备In2Se3预制层工艺中3个主要条件,即衬底材质、Se源温度、衬底温度进行研究.分析讨论上述3种因素对In2Se3薄膜的结晶生长和择优取向生长的影响.发现:在Mo/苏打石灰玻璃(Mo/SLG)衬底上生长,Se源温度在270℃以上或衬底温度为380～400℃的较高温度时,制备的In2Se3预制层是单一晶相的In2Se3,其x射线衍射峰是以(110)和(300)峰为择优取向.反之,生长在苏打石灰玻璃(SLG)衬底上,Se源温度为230℃以下或衬底温度为较低温度300℃时,In2Se3预制层结晶质量较差,其X射线衍射峰则多以In2Se3(006)衍射峰为择优取向.     

用几何靶溅射方法制备AlSb多晶薄膜

采用Al-Sb几何靶用直流磁控溅射方法沉积了AlSb薄膜(衬底温度为30%和200℃),然后在N_2气氛下,300～540℃,对沉积的薄膜进行退火.用X射线衍射分析了AlSb薄膜的结构,用X射线荧光光谱法测定了Al和Sb的原子比,用原子力显微镜观察了表面形貌.结果表明:几何靶可以很好地控制薄膜中Al和Sb原子的比例.制备的ALSb薄膜经过退火之后形成了面心立方结构的AlSb半导体化合物,平均晶粒大小约28rm.较高的退火温度有利于AlSb薄膜的晶粒生长.     

不同扩散阻挡层对柔性钛衬底CZTSSe薄膜与电池性能的影响

研究不同扩散阻挡层对柔性钛衬底CZTSSe薄膜和电池性能的影响。X射线衍射(XRD)和拉曼光谱结果表明适当扩散阻挡层的引入可提高CZTSSe薄膜(112)择优取向和结晶性,还可抑制TiSe杂相的生成。CZTSSe结晶性的提高得益于扩散阻挡层表面较小的粗糙度。Cr、ZnO和TiN这3种不同阻挡层中,TiN层对TiSe杂相的抑制作用最强,用它作为扩散阻挡层制备的柔性CZTSSe薄膜结晶性最好,(112)晶面择优取向最强,电池性能最佳且转换效率相对无阻挡层电池提高了67%。     

用于太阳电池吸收层CuInS2薄膜的RF反应溅射制备及其表征

该文报道采用射频反应溅射技术，以铜银合金为靶材、H2S为反应气体，在Soda-Lime玻璃衬底上沉积高质量CuInS2薄膜的实验结果。分别运用扫描电镜、能量散射X—射线谱、X—射线衍射谱和表面轮廓仪等对沉积样品的结构形貌和组成成分等特性进行了分析表征，研究了这些特性对沉积参数的依赖关系。通过对溅射功率、衬底温度和H2S流量等工艺参数的优化，获得了单一黄铜矿相结构且沿单一晶向(112)生长的高质量富铜薄膜，晶粒线度达400nm，薄膜中成分的原子比[Cu In]／[S]和[Cu]／[Cu In]可分别接近于1和0．5，并对结果进行了简单讨论。该技术成本低廉、可靠性高，适合于高效太阳电池吸收层薄膜的高均匀度大面积沉积，具有规模化工业生产的推广价值。     

纳米线织构的多晶硅太阳电池研究

采用无电化学刻蚀技术,通过优化Ag NO_3浓度、刻蚀温度和刻蚀时间,研究在125 mm×125 mm多晶硅片表面制备均匀分布硅纳米线阵列的方法,获得了硅纳米线织构的多晶硅在宽光谱范围内(300~1000 nm)平均反射率约为8%。成功制备了表面具有硅纳米线织构的多晶硅太阳电池,并通过两种改进方法提高太阳电池效率:1)优化硅纳米线阵列的长度(约1.5μm),并利用PECVD方法在硅纳米线阵列表面生长70 nm Si_3N_4薄膜进行表面钝化,纳米线织构的多晶硅太阳电池效率从8.95%提高到了11.41%。2)使用HNO_3和HF混合溶液去除硅衬底背表面的硅纳米线阵列,使铝背电极与多晶硅紧密接触,太阳电池效率进一步提高到13.99%。研究表明:所采用的改进方法能有效提高纳米线织构多晶硅太阳电池的效率。     

PECVD法SiNx:H薄膜减反钝化特性研究

利用射频等离子体增强化学气相沉积法制备了在太阳电池中用作表面钝化和减反层的SiNx:H薄膜.制备的折射系数分布在1.72 ～2.55范围内的一系列薄膜对电阻率为10Ω·cm的p型衬底硅片具有较好的钝化效果.研究给出了SiH4/NH3流量比和衬底温度对薄膜折射系数和钝化效果的影响规律,当衬底温度为300℃,SiH4/NH...     

透明弹性薄膜调节可见光透射比的试验研究

总结了透明弹性薄膜调节可见光的研究试验。基本原理是当光通过凸凹不平的透明薄膜时，在薄膜表面要发生散射，散射能力大致与薄膜表面粗糙度成正比。当通过外力来改变薄膜表面的粗糙度时，就可以改变薄膜的散射比，也即改变了薄膜的直射透射比，从而对透射光强进行一定的调节。实验表明：采用适当硬度的透明弹性薄膜，在一个大气压条件下，薄膜的直射透射比的调节范围可从最小33％达到最大86．7％，透射比的改变时间不超过1秒。这一效果比目前所报道的电致变色调光的范围要大，速度要快，视觉效果也好的多，有一定的应用前景。     

STRUCTURAL AND MICROSTRUCTURAL EFFECTS ON THE THERMAL CONDUCTIVITY OF ZIRCONIA THIN FILMS

Thermal properties of thin films are involved in a large number of applications such as electronic and electrooptical devices, or thermal barrier coating. It is known that the structure and the microstructure of thin solid films have a strong influence on the thermal conductivity, which may be considerably lower than for bulk materials. The aim of this study is to highlight the role of structure and microstructure on the thermal conductivity of ZrO 2 thin films (stabilized with Y 2 O 3 or not). Investigations have focused on the influence of film thickness, substrate roughness, and crystallites size on the thermal properties of dielectric thin film samples. For this purpose, a new photothermal method has been developed to measure the thermal conductivity of such films on various kind of substrates with an accuracy better than 10%. It has been observed that a decrease in the dielectric thickness leads to a drastic drop of the apparent thermal conductivity, k a , whatever the ZrO 2 phase is. k a is affected by an additional thermal resistance, R fs , especially between ZrO 2 and alumina substrate. This resistance R fs varies linearly with the substrate roughness. Finally, the influence of crystallite size and grain boundaries on k a have been shown.     

Photo-rechargeability of film electrodes prepared by pulsed laser deposition

The film electrodes of TiO₂, which have two functions of opto-electric conversion and storage of electrochemical energy, were prepared by pulsed laser deposition. To investigate the relationship between the photo-rechargeability and the surface structure, the TiO₂ film electrodes with different surface morphology were prepared by changing the inert gas pressure during the deposition. The photo-charged quantity was found to be proportional to the third power of the rms of surface roughness. The results suggest that not only the surface but also the interstices between crystal grains near the surface contribute to the photo-charging with low photo-emf.     

PEN as substrate for new solar cell technologies

The possible use of polyethylene naphthalate as substrate for low-temperature deposited solar cells has been studied in this paper. The transparency of this polymer makes it a candidate to be used in both substrate and superstrate configurations. ZnO:Al has been deposited at room temperature on top of PEN. The resulting structure PEN/ZnO:Al presented good optical and electrical properties. PEN has been successfully textured (nanometer and micrometer random roughness) using hot-embossing lithography. Reflector structures have been built depositing Ag and ZnO:Al on top of the stamped polymer. The deposition of these layers did not affect the final roughness of the whole. The reflector structure has been morphologically and optically analysed to verify its suitability to be used in solar cells.     

ZnO:Al绒面透明导电薄膜的制备及分析

利用中频脉冲磁控溅射方法,采用Al掺杂(质量百分比2%)的Zn(纯度99.99%)金属材料为靶材制备平面透明导电ZnO:Al(ZAO)薄膜。利用湿法腐蚀方法,将平面ZAO薄膜在0.5%的稀盐酸中浸泡一定时间后,形成表面凹凸起伏的绒面结构。研究了平面ZAO薄膜的结构特性以及衬底温度、溅射功率和腐蚀时间对绒面ZAO薄膜表面形貌的影响,并对腐蚀前后薄膜的电阻变化进行了分析。结果表明:高温、低功率条件下制备的绒面ZAO薄膜表面形貌较好,在硅薄膜太阳电池中具有潜在的应用前景。     

Effect of composition gradient in Cu(In,Al)Se2 solar cells

Cu(In,Al)Se₂ (CIAS) thin films were prepared by a three-stage evaporation process. In this experiment, the composition ratio of Cu/(In+Al) at the end of the second stage (Cu/III_2nd) was changed from 1.1 to 1.7. The CIAS films showed an Al distribution with a V-shape profile. The valley depth of the V-shape from the surface increased with increasing the Cu/III_2nd ratio. The valleys of the V-shape for the films with the Cu/III_2nd ratio of 1.1–1.7 were located at approximately 0.3–1.0 μm from the film surface, respectively. The rms surface roughness increased from 40 nm for Cu/III_2nd=1.1 to 90 nm at Cu/III_2nd=1.3 and then saturated for greater Cu/III_2nd ratios. Solar cells with the Al/ITO/ZnO/CdS/CIAS/Mo/soda-lime glass structure were fabricated. The fill factor was seen to decrease while the product of short-circuit current and open-circuit voltage remained constant. The reverse saturation current increased when the Cu/III_2nd ratio is greater than 1.3 which is a behavior of the surface roughness. Cu/III_2nd ratios greater than 1.3 lead to the distant position of V-shape from the surface and the increase in surface roughness.     

High quality ZnO and Ga:ZnO thin films grown onto crystalline Si (1 0 0) by RF magnetron sputtering

Undoped and 2% Ga-doped ZnO films have been deposited by RF magnetron sputtering onto single crystal Si (1 0 0) substrates equivalent to the commercial Si solar cells. The same films were also grown on amorphous silica substrates to complete their characterization. The films have been characterized by X-ray diffraction, electrical and optical measurements, X-ray photoelectron spectroscopy, Raman microspectroscopy and scanning and high-resolution transmission electron microscopy. Films present a very good quality crystalline wurtzite structure with the c-axis perpendicular to the substrate, with continuity of the (0 0 0 2) planes along the whole film, as shown by transmission electron microscopy. The doped sample shows an increase of two orders of magnitude of the electrical conductivity, an optical transmittance bigger than 85% along the visible spectrum, a diminution of the grain size in the direction parallel to the substrate and a lower surface roughness. The Ga-cations act only as substitutional impurities, they are homogeneously distributed in the whole film, maintaining the wurtzite structure and increasing the carrier density. The formation of any spurious phase or segregation of Ga₂O₃ clusters that can act as carrier traps can be discarded. The characterization results allow us to conclude that the doped film has improved electrical and optical properties with respect to the undoped one. Therefore, the Ga-doped films are very suitable candidates as transparent conducting electrodes for solar cells, displays and other photoelectronic devices.     

Growth and characterization of ZnO thin films prepared by electrodeposition technique

ZnO thin films were deposited on either indium tin oxide-coated glass or copper substrate by the electrodeposition process, using zinc chloride and flowing air as precursors. The effect of pH on the structural and morphological ZnO films was studied and the optimum deposition conditions have been outlined. The kinetics of the growth of the films have been investigated. We note that the rate of deposition of ZnO in an acidic solution was larger than in a basic solution. The structure of the films was studied using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The surface morphology and thickness of the films were determined using scanning electron microscopy. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure (zincite) at pH 4. The optical transmittance of ZnO decreases with varying film thickness. The optical energy bandgap was found to be 3.26 eV.     

Heat transfer enhancement in light-emitting diode packaging employing different molar concentration of magnesium oxide thin films as a heat spreader

To solve thermal management difficulties created by miniaturization of light-emitting diode package, magnesium oxide thin film was spin coated on the aluminum 5052-grade substrate and employed for heat spreading and improvement of the thermal path for heat removal from light-emitting diode parcel to ambient. Thickness of different films of magnesium oxide was prepared from 0.6M and 0.8M precursors to find out the effects of films thickness and molar concentrations towards perfect heat spreading. Results from X-ray diffraction (XRD) proves the MgO thin film as cubic with the crystalline orientations of (200), (220), and (222). Good results were highlighted through 20 layers (0.6M) MgO thin film in respect to its transient thermal analysis compared with other layers from 0.6M and 0.8M and bare Al substrate; this was due to its nonporous and evenly distributed particles size (56.0 nm), film thickness (301.7 nm), surface roughness (121 nm), higher thermal conductivity (26.3 W/mK), and free from internal cracks and defects. Lower total thermal resistance (11.4 K/W), lower junction temperature (98.8°C), optimal thermal impedance (36.43°C), higher illumination from light-emitting diode, and operation within safe operating temperature range (2700-3000 K) for high-power light-emitting diodes were all recorded at 700 mA from the tested light-emitting diode mounted on 20 layers (0.6M) magnesium oxide thin film. This study consequently proved magnesium oxide thin film as an alternative heat spreader in lighting technology packaging.