硫化温度对ZnS薄膜生长质量的影响

采用热反应法对玻璃衬底上以磁控溅射制备的Zn薄膜进行硫化,制备出ZnS薄膜。薄膜的微观结构、物相结构和表面形貌分别采用正电子湮没技术（PAT）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）进行分析和表征。利用慢正电子湮没多普勒展宽对四个不同硫化温度下得到的ZnS薄膜样品中膜层结构缺陷进行研究,测量了薄膜中的空位型微观缺陷的相对浓度,指出445℃硫化样品中正电子注入能量在1.5~4.5 keV后S参数最小,说明该硫化温度下反应生成的ZnS薄膜结构缺陷浓度最小,膜的致密度最高。XRD结果显示薄膜在445℃以上硫化后,呈（111）择优生长趋势。从扫描电镜的结果也可以看出,在445℃硫化后,薄膜的晶粒明显地变得更大、更致密,这是因为ZnS晶胞比Zn晶胞大以及硫化过程中ZnS固相再结晶的缘故。ZnS thin films have been prepared by sulfurizing zinc thin films deposited on glass substrate by magnetron sputtering for two hours. The microstructure defects, crystallizations and surface morphology of zinc films sulfurized at different temperature were analyzed by PAT (positron annihilation technique), XRD(X-ray diffraction) and SEM (Scanning electron microscopy), respectively. For analyzing the structure defect of four samples with different sulfurization temperature, PAT has been used to obtain the relative concentration of defects. With the positron energy range of 1.5~4.5 keV, the S parameter of ZnS films is minimum. It demonstrates that ZnS films produced at 445℃ have the minimum structural defect concentration and the highest density. XRD results show that films are blende structure with the preference of (111) orientation above 445℃. And from the result of SEM, because of ZnS films recrystallization, the crystal grains obviously become large and dense at 445℃.     

不同硫压退火对溅射沉积ZnS薄膜性能的影响

ZnS作为一种宽带隙半导体,以其优异的光电性能近年来受到广泛关注,在太阳能电池、光催化剂以及传感器方面有着广阔的应用前景.本文首先以射频磁控溅射方法沉积了ZnS薄膜,然后在600℃温度和不同硫压下进行退火,通过X射线衍射、扫描电子显微镜、能量散射X射线谱、紫外-可见透射光谱以及慢正电子多普勒展宽谱对ZnS薄膜的晶体结构、表面形貌、晶粒尺寸、成分、透光率以及缺陷进行分析.结果表明:硫气氛后退火能够改善ZnS薄膜结晶性,退火后ZnS薄膜光学带隙为3.43—3.58 eV.当硫压高于0.49 atm(1 atm=1.01×10⁵ Pa)时,ZnS内部硫间隙原子以及表面单质硫降低了薄膜在可见光区的透光率.慢正电子多普勒展宽谱结果还表明,ZnS薄膜的缺陷浓度由表层到内层逐渐降低,薄膜缺陷随着硫压增加而降低.同时,3γ湮没证明了薄膜内部较为致密,硫化会导致薄膜开孔率增加.吸附硫通过内扩散占据了晶体中硫空位缺陷的位置,导致缺陷浓度降低,进而改善了薄膜质量.     

不同参数溅射的ZnO薄膜硫化后的特性

采用直流反应磁控溅射法在玻璃和石英衬底上沉积了ZnO薄膜, 然后将它们在H^２S气流中 硫化得到ZnS薄膜．用x射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和UV-VIS透过光谱对Zn S薄膜样品进行了分析．结果表明, 该ZnS薄膜为六角晶体结构, 沿(002)晶面择优取向生长, 其结晶状态和透过光谱与工作气压、Ar/O^２流量比密切相关. 当气压高于1Pa 时, 得 到厚度很小的ZnS薄膜; 而气压低于1Pa时, 沉积的ZnO薄膜则不能全部反应生成ZnS. 另外, 当Ar/O^２流量比低于4∶1或高于4∶1时, 结晶状态都会变差. 此外, 由于ZnS薄 膜具有高 的沿(002)晶面择优取向的生长特性, 使得退火或未退火ZnO薄膜硫化后的晶粒尺寸变化很小 . 关键词： ZnS薄膜 磁控溅射 ZnO硫化 太阳电池     

掺杂金刚石薄膜的缺陷研究

利用多普勒增宽谱和电子顺磁共振研究了掺硼和掺硫金刚石薄膜的缺陷状态.多普勒增宽谱的结果表明，不同杂质元素掺杂的金刚石薄膜，其中使正电子湮没的缺陷种类是相同的；正电子与不同杂质元素硼、硫之间的相互作用不明显；少量硼可使金刚石膜中的空位浓度减少.EPR结果表明，各掺杂样品的顺磁信号主要来自于金刚石的碳悬键. 关键词： 金刚石 掺杂 多普勒增宽谱 电子顺磁共振     

MgB2超导体的正电子湮没研究

本文利用正电子湮没技术(PAT)对不同密度的MgB2样品分别进行了测定,结果发现正电子在MgB2中自由态的湮没时间(本征寿命τ1)和在捕获态的湮没时间(缺陷寿命τ2)比其他高温超导体都明显要高,这反映了MgB2的体电子浓度相对于其它超导体要低,可能归因于MgB2超导材料本身的晶体结构和化学组成,MgB2超导材料的正电子寿命不仅与晶体的结构缺陷,而且与样品的密度或孔隙度有关.     

同步辐射小角X射线反射和慢正电子湮没表征low-k SiOx薄膜

利用射频磁控溅射方法制备了低介电常数材料多孔非晶SiO_x薄膜,溅射压强从1Pa—3Pa变化,傅立叶变换红外吸收光谱测行x的范围为1≤x≤1.6.同步辐射X射线反射(XRR)测量结果显示了随着溅射压强的增大,薄膜的孔隙率(体积比)从6%上升到24%,同时估计了薄膜的厚度.慢正电子湮没多普勒展宽测量探测了薄膜中的缺陷分布信息,结果显示随着溅射压强的增加,薄膜中的E'中心缺陷增加,其抑制了电子偶素的生成,从而使S参数呈下降趋势,利用VEPFIT程序对正电子湮没结果进行了拟合,得到的膜厚与XRR结果较为接近.     

ZnO退火条件对硫化法制备的ZnS薄膜特性的影响

采用反应磁控溅射法在玻璃和石英衬底上沉积了ZnO薄膜, 然后经过不同条件退火和在H22S气氛中硫化最终得到ZnS薄膜. 用x射线粉末衍射仪、扫描电子显微镜和UV—VIS分光光度计 对ZnS薄膜样品进行了分析. 结果表明, ZnO薄膜硫化后的晶体结构和光学性质取决于它的退 火条件. 真空和纯O2₂中退火的ZnO薄膜硫化后只是部分形成六角晶系结构的ZnS . 而在空气 和纯N2₂中退火的ZnO薄膜则全部转变为ZnS, 在可见光范围内的光透过率 关键词： ZnS薄膜 磁控溅射 ZnO硫化 太阳电池     

MgB2超导体的正电子湮没研究

本文利用正电子湮没技术（PAT）对不同密度的MgB2样品分别进行了测定，结果发现正电子在MgB2中自由态的湮没时间（本征寿命τ1）和在捕获态的湮没时间（缺陷寿命τ2）比其他高温超导体都明显要高，这反映了MgB2的体电子浓度相对于其它超导体要低，可能归因于MgB2超导材料本身的晶体结构和化学组成，MgB2超导材料的正电子寿命不仅与晶体的结构缺陷，而且与样品的密度或孔隙度有关．     

Hg1-xCdxTe晶体缺陷的正电子湮没寿命

利用正电子(e⁺)湮没寿命谱实验研究了Hg_1-xCd_xTe晶体样品的空位缺陷.碲溶剂法生长的样品，不论是n型导电还是p型导电都存在大量的Hg空位.经过合适的退火工艺，p型材料转为n型，同时对正电子的俘获效应减小，表现为正电子湮没平均寿命值减小14—17ps.若退火温度高于350℃，正电子湮没寿命值又增大，表明Hg空位浓度增加.得到HgCdTe中正电子的体寿命为τ_b=272ps.根据正电子湮没寿命和电参数的测量结果，得出 关键词：     

Pulsed Laser Deposition ZnS Buffer Layers for CIGS Solar Cells

采用脉冲激光沉积(PLD)技术,在20、200、400和600 oC下制备出了高质量的ZnS薄膜．XRD分析结果表明,PLD法制备的ZnS多晶薄膜为立方闪锌矿结构而并非Murali报道的六方的纤锌矿结构,并沿(111)方向择优取向生长．Raman光谱进一步证明了在350 cm-1出现了立方相ZnS薄膜的A1振动模式．通过ZnS薄膜的SEM平面和断面图可观察到采用PLD技术生长出了非常密实、光滑、均匀的薄膜．PLD生长的ZnS薄膜的颗粒远小于化学浴沉积的CdS颗粒,这也是影响其电池效率的主要原因．XRF化学组成分析结果表明ZnS薄膜符合化学计量比,但略微富S．最后通过光吸收谱测得不同温度下的ZnS薄膜的光学带隙在3.2～3.7 eV,并随薄膜沉积温度的升高,光学带隙反而增加．采用宽带隙的ZnS缓冲层材料,与CdS(2.4 eV)相比,可以增加电池蓝波段的响应．     

Effect of [Zn]/[S] ratios on the properties of chemical bath deposited zinc sulfide thin films

ZnS thin films have been prepared by chemical bath deposition (CBD) technique onto glass substrates deposited at about 80 °C using aqueous solution of zinc sulfate hepta-hydrate, ammonium sulfate, thiourea, ammonia and hydrazine hydrate. Ammonia and hydrazine hydrate were used as complexing agents. The influence of the ratio of [Zn]/[S] on formation and properties of ZnS thin films has been investigated. The ratio of [Zn]/[S] was changed from 3:1 to 1:9 by varying volumes and/or concentrations of zinc sulfate hepta-hydrate and thiourea in the deposition solution. The structural and morphological characteristics of films have been investigated by X-ray diffraction (XRD), scanning electron microscope and UV-vis spectroscopic analysis. ZnS films were obtained with the [Zn]/[S] ratio ranged from1:1 to 1:6. In the cases of [Zn]/[S] ratio ≥ 3:1 or ≤1:9, no deposition was found. Transparent and polycrystalline ZnS film was obtained with pure-wurtzite structure at the [S]/[Zn] ratio of 1:6. The related formation mechanisms of CBD ZnS are discussed. The deposited ZnS films show good optical transmission (80-90%) in the visible region and the band gap is found to be in the range of 3.65-3.74 eV. The result is useful to further develop the CBD ZnS technology.     

溶液pH值对化学浴法制备的Cd_xZn_(1-x)S薄膜光电性能的影响

采用氯化镉、氯化锌、硫脲、柠檬酸钠和氨水的溶液体系通过化学浴沉积法合成Cd_xZn_(1-x)S薄膜,利用X射线衍射分析、扫描电子显微镜、能谱仪和紫外可见近红外分光光度计等表征手段研究了Cd_xZn_(1-x)S薄膜的形貌、相结构和光学性能,测试了薄膜的光电流响应曲线并对薄膜的光电性能进行了分析.结果表明:在pH值为10至13范围内成功制备了均匀的Cd_xZn_(1-x)S薄膜;随着pH值升高,薄膜中Zn原子比例与光学带隙减小;制备的薄膜均表现出明显的光电导现象.pH值为11和12时薄膜的表面最为平整致密,结晶性最好,光学带隙分别为2.92eV和2.72eV,光暗电导比均为1.20,光源关闭后电流下降过程最快,10s后电流分别下降了约68.55%和69.39%.     

Investigation of structural,optical and electrical properties of ZnS thin films prepared by nebulized spray pyrolysis for solar cell applications

Zinc sulfide (ZnS) thin films have been deposited on microscopic glass and fluorine doped tin oxide substrates by nebulized spray pyrolysis technique with different substrate temperature and molar concentration. The structural, morphological, optical and electrical properties of the prepared ZnS thin films have been studied using X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), UV–Vis spectrophotometer and Hall effect measurement. XRD patterns confirm that the prepared films are hexagonal wurtzite structure, with (100) as preferred orientation. The structural parameters such as crystallite size, dislocation density and microstrain have been calculated from XRD study. Hydrophilic and hydrophobic nature is revealed by contact angle measurements. FESEM image of the ZnS thin films show smooth and uniform spherical grains are uniformly arranged on the films surface. Optical transmittance spectrum illustrate that the ZnS films were high transparent in the visible region and gets absorbed in the UV region. The optical band gap value of the ZnS thin films decreased with the increasing substrate temperature. The average transmittance is found to be 82% and direct band gap value is 3.56 eV at 400 °C for set D. The Activation energy of the prepared ZnS films was determined from the graph between ln (ρ) versus temperature (K^?1) using a four-probe method.     

Enhanced visible-light photoactivity of La-doped ZnS thin films

ZnS and La-doped ZnS thin films were successfully synthesized using chemical-bath deposition on conductive glass substrates. The effects of La-doping on the surface morphology, composition, structure and optical properties of the films were investigated. The photocatalytic performances of undoped and doped ZnS films were evaluated by photodegrading methyl orange aqueous solution under both ultraviolet-light and visible-light irradiation. The results show that the stoichiometry ratio and the properties of ZnS can be tailored by the La-doping concentration. An appropriate amount of La-doping effectively extends the absorption edge to visible-light region, which leads to the significant enhancement of the photocatalytic activity of ZnS thin films under visible-light irradiation. The mechanism of enhanced visible-light photoactivity by La-doping is briefly discussed. The present study provides a simple method for designing the highly efficient semiconductor photocatalysts that can effectively utilize sunlight.     

Green route fast synthesis and characterization of chemical bath deposited nanocrystalline ZnS buffer layers

Zinc sulphide (ZnS) thin films are deposited using chemical bath deposition method on the glass substrates in an aqueous alkaline reaction bath of zinc acetate and thiourea along with non-toxic complexing agent tri-sodium citrate at 95 °C. The results show noteworthy improvement in the growth rate of the deposited ZnS thin films and thickness of the film increases with the deposition time. From X-ray diffraction patterns, it is found that the ZnS thin films exhibit hexagonal polycrystalline phase reflecting from (101) and (0016) planes. The high resolution transmission electron microscopy studies confirmed the formation of hexagonal phase from the d-value calculation which was 0.3108 nm. X-ray photoelectron spectroscopy reveals that the Zn–S bonding energy is at 1022.5 and 162.1 eV for Zn 2p_3/2 and S 2p_1/2 states, respectively. Field emission scanning electron microscopy study shows that deposited thin films are highly uniform, with thin thickness and completely free from large ZnS clusters which usually form in aqueous solutions. Atomic force microscopy investigates that root mean square values of the ZnS thin films are from 3 to 4.5 nm and all the films are morphologically smooth. Energy dispersive spectroscopy shows that the ZnS thin films are relatively stoichiometric having Zn:S atomic ratio of 55:45. It is shown by ultraviolet–visible spectroscopy that ～90% transmittance and ～10% absorbance for the ZnS films in the visible region, which is significantly higher than that reported elsewhere and the band gap energy of the ZnS films is found to be 3.76, 3.74, and 3.71 eV, respectively.     

金刚石膜微结构的慢正电子束测量研究

用慢正电子束辅助以拉曼光谱方法对一批较高质量的PECVD金刚石膜的微结构进行测量研究．拉曼光谱实验结果显示,这批金刚石膜中金刚石相含量比较高,正电子湮没实验进一步从微观结构上指出各个金刚石膜之间存在很大差异,并且从缺陷角度发现各样品中缺陷尺寸和缺陷浓度不一样,造成膜质量不同．S-E曲线变化趋势反映出各样品金刚石晶体结构存在明显不同．这表明正电子湮没技术是测量金刚石膜微结构的有力手段．     

Evolution of Structural Defects in SiOx Films Fabricated by Electron Cyclotron Resonance Plasma Chemical Vapour Deposition upon Annealing Treatment

We study the structural defects in the SiO, film prepared by electron cyclotron resonance plasma chemical vapour deposition and annealing recovery evolution. The photoluminescence property is observed in the as-deposited and annealed samples. [-SiO3]^2- defects are the luminescence centres of the ultraviolet photoluminescence （PL） from the Fourier transform infrared spectroscopy and PL measurements. [-SiO3]^2- is observed by positron annihilation spectroscopy, and this defect can make the S parameters increase. After 1000℃ annealing, [-SiO3]^2- defects still exist in the films.     

A study of the optical properties and adhesion of zinc sulfide anti-reflection thin film coated on a germanium substrate

To conduct this study, zinc sulfide (ZnS) thin films deposited on germanium (Ge) substrates were prepared by an evaporation method. The effects of deposition rate and annealing on the optical properties and adhesion of the ZnS thin films were investigated. The transmission intensity and the X-ray diffraction (XRD) pattern of the samples showed that the transmittance of the samples decreases by increasing the evaporation rates. However, with the increase of the annealing temperature, crystallinity of the thin films improves which, in turn, results in the enhancement of the transmission intensity in a far infrared region. The maximum grain size was obtained at the annealing temperature of 225 °C. Our experimental results also show that evaporation rate and annealing influences the adhesion of ZnS thin films to Ge substrates.     

CdS/ZnS core–shell nanoparticles in arachidic acid LB films

Core–shell CdS/ZnS nanoparticles in arachidic acid film were prepared through a novel Langmuir–Blodgett (LB) approach. Post-deposition treatment of the precursor LB multilayers of cadmium arachidate with H₂S gas followed by intercalation of Zn²⁺ ions and further sulfidation result in the formation of CdS/ZnS nanoparticles in the LB film. The formation of these nanoparticles and resulting changes in layered structures were studied by FTIR and X-ray reflection measurements. The optical properties were studied using UV–vis absorption and photoluminescence spectroscopy. A red-shift in the absorption spectrum and enhancement of CdS excitonic emission together with reduction of surface states emission suggest that after the intercalation step, a thin layer of ZnS surrounds the CdS nanoparticles, thus forming a core–shell structure. Subsequent to the second sulfidation, a further red-shift in absorption suggests the formation of a thicker ZnS coating on CdS. Electron diffraction of CdS nanoparticles coated with thicker ZnS showed the diffraction patterns of only ZnS, as expected for core–shell structures.