衬底温度对PLD方法制备的ZnO薄膜的光学和电学特性的影响

利用脉冲激光沉积法(PLD)在c面蓝宝石衬底上制备了ZnO薄膜并对其进行了X射线衍射(XRD)、反射式高能电子衍射(RHEED)、光致发光(PL)谱和霍尔(Hall)测试.RHEED和XRD分析表明,温度在350℃至550℃之间时,ZnO薄膜的结晶质量随着衬底温度的升高而提高,当衬底温度进一步升高后,ZnO薄膜的结晶质量开始下降.四个样品中,衬底温度为550℃的样品具有最清晰的规则点状RHEED图像和半高宽最窄的(0002)衍射峰.PL谱和Hall测量的结果表明,衬底温度为550℃的样品还具有最好的发光性质和最大的霍尔迁移率.     

CdS多晶薄膜的制备与光学性质研究

采用电子束蒸发法制备CdS多晶薄膜,研究了衬底温度和退火方式对薄膜光学性质的影响。XRD测试显示,制备样品为六方相多晶结构,沿(002)晶向择优取向生长,在200℃衬底温度时具有最大的择优取向度。对样品的紫外-可见透过谱测试表明,随着衬底温度的升高,薄膜的光吸收边逐渐变陡,光学带隙逐渐增大。退火后,CdS薄膜光吸收边变的更加陡直,光谱透过性能进一步提升,但光学带隙变化很小。此外,制备样品的XRD谱、光吸收边和光学带隙在250℃衬底温度下出现反常变化。同时对上述变化产生的根源进行了分析和讨论。     

衬底温度对共蒸发制备GaSb多晶薄膜性质的影响

采用共蒸发的方法在玻璃衬底上制备出GaSb多晶薄膜材料.研究了薄膜生长速率与衬底温度、Ga源温度和Sb源温度的关系.通过XRD、UV-Vis、Hall效应和AFM等测试方法,研究了衬底温度对于GaSb薄膜的结构特性、光电性质以及表面形貌的影响.GaSb多晶薄膜具有(111)择优取向,薄膜的吸收系数达到105 cm-1,晶粒尺寸随衬底温度升高逐渐增大;衬底温度为540℃时,薄膜的迁移率达到127 cm2/V·s,空穴浓度为3×1017 cm-3.GaSb薄膜的表面粗糙度随温度增加而增加.     

衬底温度对Al掺杂ZnO薄膜结构及其光电性能的影响

利用溅射方法制备了Al掺杂ZnO(AZO)薄膜,探究了衬底温度对薄膜的形貌特征、结构和光电性能的调控.实验结果表明:衬底温度可以调控AZO薄膜的生长方式以及光电性能.随着衬底温度的升高,AZO薄膜从无规则的形状转变为球形并且其颗粒尺寸逐渐减小.XRD分析表明样品的结晶质量随着衬底温度的升高而变佳.透射光谱研究发现,在低衬底温度下,400 nm附近处有一吸收台阶,随着衬底温度升高,此吸收台阶消失,表明衬底温度影响着AZO内部的缺陷.电学性质研究表明随着衬底温度升高,AZO薄膜的导电性能也随着升高,电阻率从9×10-2 Ω·cm降到5×10-3 Q·cm.而其载流子浓度从6×1019 cm-3增加到2.2×1020 cm-3.     

气相平衡扩散法制备β-BBO薄膜

用气相平衡扩散(VTE)法在α-偏硼酸钡单晶衬底上成功地制备出β-偏硼酸钡薄膜.使用X射线衍射技术(XRD)测试了样品的衍射峰,并比较了不同温度、不同保温时间、不同衬底方向对薄膜的影响.     

LiAlO2衬底上ZnO薄膜的溶胶-凝胶法制备和表征

采用溶胶凝胶法在LiAlO2(302)衬底上制备了ZnO薄膜.用X射线衍射(XRD)和扫描电镜(SEM)对样品的结构和形貌进行了表征.XRD结果表明,随着热处理温度的升高(350℃、450℃、550℃、600℃、800℃),所得到的薄膜分别为单相ZnAl2O4(350℃),ZnAl2O4和ZnO的混合相(450℃)以及单相的ZnO(550℃、600℃、800℃),并且ZnO薄膜c轴择优取向的生长趋势随温度升高相应明显.SEM图像显示,随着热处理温度的升高,ZnO薄膜的粒径相应变大.     

在钛酸锶衬底上外延生长ZnO薄膜及其性能研究

用脉冲激光淀积法(PLD)在(111)面SrTiO3衬底上外延生长ZnO单晶薄膜.样品分别在衬底温度为350℃、500℃、600℃下外延生长.X射线衍射(XRD)的结果表明,所得的ZnO单晶薄膜结晶性能好,只出现(002)和(004)两个衍射峰,(002)峰的半高宽度(FWHM)为0.23°.在荧光光谱中我们只观察到来源于带边激子跃迁的强UV发射,并且随着生长温度的升高,紫外峰的强度逐渐增强.样品的SEM图像表明所得ZnO薄膜表面平整,晶粒均匀.衬底温度为600℃时,所得到的ZnO薄膜结构完整,晶粒尺寸最大,均匀;而且紫外发射最强.     

PECVD法制备不同衬底微晶硅薄膜的研究

采用等离子体增强化学气相沉积(PECVD)法分别在玻璃衬底和p型薄膜硅衬底上制备了微晶硅薄膜。使用拉曼谱仪、紫外-可见分光光度计、傅里叶红外光谱仪等对微晶硅薄膜进行检测,重点研究了硅烷浓度、衬底温度对薄膜沉积速率和晶化率的影响。实验结果表明:两种衬底上薄膜的沉积速率均随硅烷浓度的增大、衬底温度的升高而变大。硅烷浓度对两种衬底的薄膜晶化率影响规律相同,即均随其升高而降低;但两种衬底的衬底温度影响规律存在差别:对玻璃衬底而言,温度升高,样品晶化率减小;而p型薄膜硅衬底则在温度升高时,样品晶化率先增大后减小。此外还发现,晶化率与薄膜光学性能及含氧量存在较密切关联。     

退火温度对La3Ga5SiO14薄膜结构及表面形貌的影响

采用脉冲激光沉积技术在Si(100)衬底上制备了La3Ga5SiO14薄膜,并研究了不同的退火温度对薄膜结构和表面形貌的影响.衬底温度为室温时生长的薄膜经过800 ℃以上的高温退火后,由最初的无定形态转变为无规则取向的多晶结构.衬底温度为400 ℃时生长的薄膜经过800 ℃退火处理后呈现无序的多晶形态.当退火温度进一步升高至1000 ℃时,XRD图谱显示薄膜由最初的(220)和(300)两个结晶方向转变为以(200)和(400)为主要取向的多晶结构.表面形貌分析表明:衬底温度为400 ℃时,随着退火温度的升高,薄膜颗粒尺寸逐渐增大,表面无裂纹,而衬底温度为室温时生长的薄膜退火后则出现大量的裂缝、孔洞等缺陷.     

衬底温度对nc-Si∶H薄膜微结构和氢键合特征的影响

采用射频等离子体增强型化学气相沉积(RF-PECVD)技术,以H2和SiH4作为反应气体源,在不同的衬底温度下沉积了nc-Si∶H薄膜.采用Raman散射、X射线衍射、红外吸收等技术分析了薄膜的微结构和氢键合特征.结果表明,随衬底温度的升高,nc-Si∶H薄膜的沉积速率不断增大,晶化率和晶粒尺寸增加,纳米硅颗粒呈现出Si(111)晶面的择优生长趋势.键合特性显示,薄膜中的氢含量随衬底温度升高而逐渐减小,薄膜均匀性先增大后减小.     

气压对VHF-PECVD制备的μc-Si∶H薄膜特性影响的研究

本文主要研究了用VHF PECVD方法制备的不同工作气压的微晶硅薄膜样品。结果表明 :沉积速率随反应气压的增大而逐渐增大 ;光敏性 (光电导 /暗电导 )和激活能测试结果给出了相同的变化规律 ;傅立叶红外测试、X射线衍射和室温微区喇曼谱的结果都表明了样品的晶化特性 ;通过工艺的具体优化得出了器件级的微晶硅材料     

Microcrystalline silicon prepared at magnetic field modified nucleation

We present a complex characterization of thin silicon films, the growth of which has been influenced by permanent magnet, placed under the substrate. The pattern of microcrystalline regions in otherwise amorphous film varied with the orientation of the magnetic field. Study by atomic force microscopy and by micro-Raman spectroscopy revealed that the microcrystalline regions resulted from increased nucleation density of crystalline grains at the locations where the magnetron effect could be expected. This phenomenon allowed us to study in detail the transition between amorphous and microcrystalline growth. Moreover, it can be used as a kind of ‘magnetic lithography’ for preparation of predefined microcrystalline patterns in otherwise amorphous silicon films.     

The effect of crystallization on doping efficiency in a-Si:H films

The structure of A-Si:H films can be changed by substitutional doping of boron and phosphours dopants. Proper regulation of technological parameters, Ts and r. f. power, can result in a mode transformation from amorphous morphology into microcrystalline or polysilicon like one. The crystallization of amorphous silicon film leads to a further reduction in its room-temperature resistivity by about three order of magnitude and a reduction in its activation energy of electrical conductivity.     

Preparation of microcrystalline silicon solar cells on microcrystalline silicon carbide window layers grown with HWCVD at low temperature

N-type microcrystalline silicon carbide layers prepared by hot-wire chemical vapor deposition were used as window layers for microcrystalline silicon n–i–p solar cells. The microcrystalline silicon intrinsic and p-layers of the solar cells were prepared with plasma-enhanced chemical vapor deposition at a very high frequency. Amorphous silicon incubation layers were observed at the initial stages of the growth of the microcrystalline silicon intrinsic layer under conditions close to the transition from microcrystalline to amorphous silicon growth. ‘Seed layers’ were developed to improve the nucleation and growth of microcrystalline silicon on the microcrystalline silicon carbide layers. Raman scattering measurement demonstrates that an incorporation of a ‘seed layer’ can drastically increase the crystalline volume fraction of the total absorber layer. Accordingly, the solar cell performance is improved. The correlation between the cell performance and the structural property of the absorber layer is discussed. By optimizing the deposition process, a high short-circuit current density of 26.7 mA/cm² was achieved with an absorber layer thickness of 1 μm, which led to a cell efficiency of 9.2%.     

本征微晶硅薄膜和微晶硅电池的制备及其特性研究

本文对VHF-PECVD制备的本征微晶硅薄膜和电池进行了电学特性和结构特性方面的测试分析研究.电学测试结果给出制备薄膜的激活能为0.51eV,符合电池对材料的电学参数要求;拉曼散射谱测试结果计算得到样品的晶化率为63;;X射线衍射结果也证明材料晶化,同时(220)方向择优;首次在国内用VHF-PECVD方法制备出效率为5;的微晶硅电池(Jsc=21mA/cm2,Voc=0.46V,FF=51;,Area=0.253cm2).     

微米及纳米WC-Co基BDD污水处理电极的制备研究

硼掺杂金刚石(BDD)是高级氧化法污水处理领域的一种电极材料，其衬底材料的选择是电极涂层制备的核心问题之一，良好的衬底材料可提高膜基结合力，从而延长电极的使用寿命。本文提出以热膨胀系数较小的WC-Co为衬底，采用热丝化学气相沉积(HFCVD)法制备微米、纳米两种表面形貌的BDD电极，并利用场发射扫描电子显微镜(FE-SEM)、拉曼光谱、X射线光电子能谱(XPS)、循环伏安法对两种电极的物理性能、表面状态及电化学性能进行表征，研究结果表明：在沉积速率方面，微米薄膜是纳米薄膜的1.5倍，但纳米薄膜具有更小的残余应力，仅为-0.6 GPa;两种电极在0.5 mol/L的H₂SO₄溶液中均展现较宽的电化学窗口(约为3.7～3.9 V)和极小的背景电流，在K₃[Fe(CN)₆]氧化还原系统中表现出良好的准可逆特性，这些特性均与常规Si、Nb、Ti基BDD电极相似。在此基础上，本文对两种电极开展了苯酚模拟废水处理和加速寿命试验(ALT),结果显示：相同参数下，纳米电极在ALT中使用寿命约为423 h,明显优于微...     

微晶硅薄膜纵向不均匀性的Raman光谱和AFM研究

本文研究了采用VHF-PECVD技术制备的微晶硅薄膜的纵向均匀性.喇曼测试结果显示:微晶硅薄膜存在着生长方向的结构不均匀,随厚度的增加,材料的晶化率逐渐变大;不同衬底其非晶孵化点是不一样的,对于同一种衬底,绒度大相应的晶化率就大,对应着孵化层的厚度小;AFM测试结果明显的给出:材料的结构随厚度增加发生变化.     

A simple quality factor for characterization of thin silicon films

Four series of intrinsic thin Si films were prepared by plasma enhanced chemical vapor deposition at standard and high growth rate conditions. We suggest a simple ‘μc-Si:H layer quality factor’ based on the ratio of subgap optical absorption coefficient values: α(1.4 eV)/α(1 eV). This ratio minimizes the light scattering effects for rough films and can serve as a reliable detection of the amorphous/microcrystalline structure transition and also as a figure of merit for the microcrystalline layer. The quality factor is evaluated for series of our samples with well known structure and also compared with samples from other laboratories with different deposition and measurement techniques.     

In-situ Raman spectroscopy used to study and control the initial growth phase of microcrystalline absorber layers for thin-film silicon solar cells

The continuous deposition of microcrystalline silicon has been monitored with in-situ Raman spectroscopy. The process and measurement settings were chosen such that one spectrum was taken during approximately 9 nm of layer growth. This allows observing the crystallinity in the initial growth phase of microcrystalline silicon absorber layers. The influence of different p-doped seed layers has been studied. Under constant deposition conditions, an initial decrease in crystallinity was observed over the first tens of nanometers. By profiling the process gas flows during the initial phase it was possible to reduce the amount of amorphous material that was detected during the initial phase of deposition.     

硅烷浓度对微晶硅太阳电池的影响

采用甚高频等离子化学气相沉积技术(VHF-PECVD)制备了系列p-i-n型微晶硅太阳电池,研究了电池有源层硅烷浓度的变化对电池性能的影响.结果发现:随着硅烷浓度的提高电池的短路电流密度先提高然后降低,转换效率与之有相同的变化趋势,而开路电压随硅烷浓度的提高而增加,这些变化来源于有源层材料结构的改变.电池的填充因子几乎不受硅烷浓度的影响,但受前电极的影响很大.不同系列电池转化效率的最高点虽然处于非晶到微晶的过渡区,但对应电池的晶化率不同.另外,研究结果也给出非晶/微晶过渡区随着辉光功率的提高和沉积气压的降低向高硅烷浓度方向转移.