Er3+注入CdTe薄膜的结构和光电性能研究

采用离子注入技术对近距离升华制备的CdTe薄膜进行Er3+掺杂研究.讨论了不同掺Er3+浓度对CdTe薄膜的结构和光电性能的影响.利用X射线衍射仪、扫描电子显微镜、紫外-可见分光光度计、霍耳效应测试系统和复阻抗分析仪对样品进行测试.结果表明,适当的掺杂量可以改善CdTe薄膜的结晶性能,降低晶界势垒高度,提高其导电性能.在一定掺杂范围内掺Er3+对CdTe薄膜的光能隙影响不大.     

TeO2-ZnO-Na2O-K2O玻璃中Er3+离子掺杂浓度对其发光及荧光寿命的影响

测量了不同掺杂浓度下Er³⁺离子在碲酸盐玻璃中的吸收光谱、发射光谱和Er3+离子的荧光寿命，计算了Er³⁺离子的发射截面σ_e,分析 了Er ³⁺离子掺杂浓度对其发光强度和荧光寿命的影响.结果表明，Er³⁺离子掺 杂浓度较低时，对其荧光强度和荧光寿命没有显著的影响；掺杂浓度高时，出现了浓度猝灭 效应，使Er³⁺离 子荧光光强度降低，荧光寿命下降.实验确定了掺杂浓度最优值，同时对浓度猝灭机制进行 了分析. 关键词： 碲锌碱玻璃 3+离子')" href="#">Er³⁺离子 掺杂浓度 发光和荧光寿命     

Yb3+敏化的Er3+/Ho3+共掺碲酸盐玻璃的上转换发光研究

用高温熔融法制备了系列Er³⁺/Yb³⁺共掺，Ho³⁺/Yb³⁺共掺，和Er³⁺/Yb³⁺/Ho³⁺三掺碲酸盐玻璃，在975nm激光抽运下三种掺杂玻璃中都出现了较强的绿光和红光上转换.研究了Yb³⁺离子对Er³⁺和Ho³⁺离子上转换发光强度的影响以及Yb³⁺→Er关键词： 3+/Yb³⁺/Ho³⁺共掺')" href="#">Er³⁺/Yb³⁺/Ho³⁺共掺 碲酸盐玻璃 光谱性质 上转换     

Er/Yb共掺硅酸盐玻璃的光致发光

采用固相反应方法，制备了Er³⁺离子浓度为0.5 at.%，Yb掺杂浓度范围为0.0— 6.0 at.%的Er/Yb共掺激光玻璃，并对激光玻璃的吸收光谱和光致荧光光谱进行了分析.研究 结果显示，Yb³⁺掺杂对Er³⁺在980 nm附近的吸收起到了非常显著的 增强作用.在 980 nm的激光抽运下，激光玻璃在1530 nm处的光致发光强度随着Yb离子浓度 的增加而先增大后减小， 当Yb³⁺离子浓度为Er³⁺离子浓度6倍时光 致发光强度达到最大值.同时还发现了Yb³⁺对Er³⁺的光致荧光光谱 的展宽作用，并讨论了荧光光谱的展宽机理. 关键词： Er/Yb共掺玻璃 光致发光 吸收光谱     

Y共掺对掺Er硅酸盐玻璃光致荧光及荧光寿命的影响

采用固相反应方法制备了Er/Y共掺激光玻璃，其中Er³⁺浓度分别为0.5at%和1.0at%，所对应的Y³⁺浓度的变化范围分别为0.0at%—2.5at%和0.0at%—5.0at%.通过吸收光谱、瞬态和稳态光致发光光谱测量，研究了Y共掺对Er³⁺吸收截面、发射截面、荧光寿命和光致荧光特征的影响.研究结果表明：Y共掺杂导致1530nm附近的吸收峰宽化，对Er³⁺的吸收起到了一定的增强作用，并且这种宽化作用随着Er关键词： Er/Y共掺玻璃 光致荧光 荧光寿命     

球磨法对不同基质上转换发光的影响

分别利用高温固相法和高能球磨法,在反应温度为1 100 ℃、反应时间为2 h的条件下合成了以Y₂O₃、La₂O₃、LiTaO₃为基质的双掺和三掺Tm³⁺、Er³⁺、Yb³⁺发光粉。XRD测试结果表明,高能球磨法制备的Y₂O₃、La₂O₃、LiTaO₃材料的相纯度高于高温固相法。用980 nm红外激光分别对两种合成方法制得的样品粉末进行发光性质的检测,结果表明高能球磨法制得样品的发光强度高于高温固相法样品。不同基质样品的上转换发光性质表现为：Tm³⁺、Yb³⁺掺杂呈蓝光;Er³⁺、Yb³⁺掺杂呈黄光;Tm³⁺、Er³⁺、Yb³⁺三掺样品的发光减弱,颜色可调。     

稀土离子掺杂的AlF3基氟化物玻璃

在800和970nm LD激发下,分别研究了Er^3＋单掺和Yb^3＋,Tm^3＋共掺的AlF₃基(AYF,AZF)玻璃中上转换发光、能量传递和浓度猝灭.在Er³⁺掺杂的AlF₃基玻璃,随着Er³⁺掺杂量的增加,红光与绿光上转换发光强度比(I_red/I_green)增加,这被认为与两个Er³⁺离子 关键词： 稀土离子 氟铝酸盐玻璃     

Ce3+对Er3+/Yb3+共掺TeO2-WO3-ZnO玻璃发光性能的影响

在Er³⁺/Yb³⁺共掺TeO₂-WO₃-ZnO玻璃中引入Ce³⁺，研究了Ce³⁺对Er³⁺1.5μm发射性能及其上转换发光性能的影响。结果表明，随Ce³⁺浓度的增加Er³⁺1.5μm波段的荧光强度先增强后降低，优化的Ce³⁺掺杂浓度在2.07×10²⁰/cm³左右；1.5μm波段的荧光寿命则随Ce³⁺浓度的增加有轻微降低，从3.4ms降到3.0ms，但Ce³⁺浓度的增加对1.5μm波段的荧光半高宽基本无影响；Er³⁺/Ce³⁺间的交叉弛豫Er³⁺(⁴I_11/2)+Ce³⁺(²F_5/2)→Er³⁺(⁴I_13/2)+Ce³⁺(²F_7/2)使玻璃的上转换发光强度大大降低，但在过高的Ce³⁺浓度下，Er³⁺/Ce³⁺间的另一交叉弛豫Er³⁺(⁴I_13/2)+Ce³⁺(²F_5/2)→Er³⁺(⁴I_15/2)+Ce³⁺(²F_7/2)则使Er³⁺⁴I_13/2能级粒子数减少，导致1.5μm波段荧光强度和荧光寿命降低. 关键词： 碲钨酸盐玻璃 发光性能 3+离子')" href="#">Er³⁺离子 3+离子')" href="#">Ce³⁺离子 交叉弛豫     

Er3+/Yb3+共掺杂铋酸盐玻璃的上转换发光和能量传递

用高温熔融法制备了Er³⁺/Yb³⁺共掺杂的45Bi₂O₃-45GeO₂-10PbO玻璃,对玻璃样品进行了光谱测试,分析了上转换发光机制和Yb³⁺→Er³⁺的能量传递效率。通过Yb³⁺离子浓度对Er³⁺离子在铋酸盐玻璃中的上转换荧光强度影响的研究,得到Er³⁺质量分数为0.5%以及Yb³⁺质量分数为2.5%时上转换发光强度最大。研究结果表明,在970nm泵浦激发下,Er³⁺/Yb³⁺共掺杂B₄₅G₄₅P₁₀玻璃在532,545,673nm处产生较强的上转换绿光和红光,是一种较为理想的上转换发光基质材料。     

Yb3+/Er3+共掺杂TeO2-WO3-ZnO玻璃的光谱性质

制备了Yb³⁺/Er³⁺共掺杂的TeO₂-WO₃-ZnO玻璃,测量了Er³⁺在玻璃中的吸收光谱和970nmLD激发下的荧光光谱、荧光寿命和上转换光谱.计算了Yb³⁺/Er³⁺间的能量传递效率和Er³⁺离子1.5μm波段的吸收截面、发射截面,并研究了其荧光强度和上转换发光与Yb³⁺掺杂浓度间的关系.结果表明,Yb³⁺共掺杂可明显提高Er³⁺离子1.5μm发射的荧光强度,实验所得Yb³⁺离子的最佳掺杂浓度为Er³⁺离子浓度的3倍,在7.28×1020ions/cm³左右.Er³⁺离子1.5μm发射的荧光半峰全宽为67～72nm;上转换红、绿光均为双光子过程,随Yb³⁺掺杂浓度的增加,上转换红、绿光强度均增强.     

Synthesis and optical characterization of nanocrystalline CdTe thin films

From several years the study of binary compounds has been intensified in order to find new materials for solar photocells. The development of thin film solar cells is an active area of research at this time. Much attention has been paid to the development of low cost, high efficiency thin film solar cells. CdTe is one of the suitable candidates for the production of thin film solar cells due to its ideal band gap, high absorption coefficient. The present work deals with thickness dependent study of CdTe thin films. Nanocrystalline CdTe bulk powder was synthesized by wet chemical route at pH≈11.2 using cadmium chloride and potassium telluride as starting materials. The product sample was characterized by transmission electron microscope, X-ray diffraction and scanning electron microscope. The structural characteristics studied by X-ray diffraction showed that the films are polycrystalline in nature. CdTe thin films with thickness 40, 60, 80 and 100 nm were prepared on glass substrates by using thermal evaporation onto glass substrate under a vacuum of 10⁻⁶ Torr. The optical constants (absorption coefficient, optical band gap, refractive index, extinction coefficient, real and imaginary part of dielectric constant) of CdTe thin films was studied as a function of photon energy in the wavelength region 400–2000 nm. Analysis of the optical absorption data shows that the rule of direct transitions predominates. It has been found that the absorption coefficient, refractive index (n) and extinction coefficient (k) decreases while the values of optical band gap increase with an increase in thickness from 40 to 100 nm, which can be explained qualitatively by a thickness dependence of the grain size through decrease in grain boundary barrier height with grain size.     

化学水浴法制备大面积CdS薄膜及其光伏应用

采用化学水浴法制备了大面积CdS多晶薄膜,研究了薄膜的形貌、结构和光学性质,结果表明,大面积CdS多晶薄膜具有良好的均匀性,通过优化CdS多晶薄膜,制成了不同CdS窗口层厚度的CdTe小面积太阳电池,减薄CdS薄膜可有效提高器件的短路电流,改善器件性能.随后,在面积30cm×40cm的衬底上制备了全面积为993.6cm²的CdTe太阳电池组件,其27个集成单元的电学性质较为均匀,太阳电池组件的光电转换效率8.13%. 关键词： 化学水浴法(CBD) CdS薄膜 CdTe太阳电池 CdTe太阳电池组件     

Synthesis of the wheat-like CdSe/CdTe thin film heterojunction and their photovoltaic applications

We report on the fabrication of wheat-like CdSe/CdTe thin film heterojunction solar cells made using a simple electrochemical deposition method and close-spaced sublimation technology on indium tin oxide (ITO) substrates. Structural, optical, and electrical properties of the wheat-like CdSe/CdTe thin film junctions were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS), ultraviolet–visible (UV–vis) absorption spectrum and Keithley 2400 analysis. A significant red-shift of the absorption edge is observed in this heterojunction. The heterostructure is composed of the wheat-like CdSe array and CdTe thin film, showing optical properties typical of type II heterostructures that are suited for photovoltaic applications. A photocurrent density of 8.34 mA/cm² has been obtained under visible light illumination of 100 mW/cm². This study demonstrates that the electrochemical deposition and the close-spaced sublimation technology, which are easily adapted to other chemical systems, are promising techniques for large-scale fabrication of low-cost heterojunction solar cells.     

CdTe薄膜太阳电池背接触的研究

用近空间升华法制备了CdTe多晶薄膜，用硝酸-磷酸(NP)混合液对薄膜表面进行了腐蚀.经SEM观测，腐蚀后的CdTe薄膜晶界变宽，XRD测试发现，经NP腐蚀后，在CdTe薄膜表面生成了一层高电导的富Te层.在腐蚀后的CdTe薄膜上分别制备了Cu，Cu/ZnTe：Cu，ZnTe：Cu，ZnTe/ZnTe：Cu四种背接触层，比较了它们对太阳电池性能的影响.结果表明，用ZnTe/ZnTe：Cu复合层作为背接触层的效果较好，获得了面积为0.5cm²，转换效率为13.38%的CdTe多晶薄膜太 关键词： 硝磷酸腐蚀 背接触层 CdTe太阳电池     

Deep level transient spectroscopy investigation of deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact

Deep levels in Cds/CdTe thin film solar cells have a potent influence on the electrical property of these devices. As an essential layer in the solar cell device structure, back contact is believed to induce some deep defects in the CdTe thin film. With the help of deep level transient spectroscopy (DLTS), we study the deep levels in CdS/CdTe thin film solar cells with Te:Cu back contact. One hole trap and one electron trap are observed. The hole trap H1, localized at E_v+0.128~eV, originates from the vacancy of Cd (V_Cd. The electron trap E1, found at E_c-0.178~eV, is considered to be correlated with the interstitial Cu_i⁼ in CdTe.     

基于氧化镍背接触缓冲层碲化镉薄膜太阳电池的研究

采用电子束蒸发法制备了NiO薄膜,并对其作为碲化镉薄膜太阳电池背接触缓冲层材料进行了相关研究.NiO缓冲层的加入使得碲化镉太阳电池开路电压显著增大.通过X射线光电子能谱测试得到的NiO/CdTe界面能带图表明NiO和CdTe的能带匹配度很好.NiO是宽禁带P型半导体材料,在电池背接触处形成背场,减少了电子在背表面处的复合,从而提高电池开路电压.通过优化NiO薄膜厚度,制备得到转换效率为12.2%、开路电压为789 mV的碲化镉太阳电池.研究证实NiO是用来制备高转换效率、高稳定性碲化镉薄膜太阳电池的一种极有前景的缓冲层材料.     

Dependence of the microstructural properties on the substrate temperature in strained CdTe (1 0 0)/GaAs (1 0 0) heterostructures

CdTe thin films were grown on GaAs (1 0 0) substrates by using molecular beam epitaxy at various temperatures. The bright-field transmission electron microscopy (TEM) images and the high-resolution TEM (HRTEM) images showed that the crystallinity of CdTe epilayers grown on GaAs substrates was improved by increasing the substrate temperature. The result of selected-area electron diffraction pattern (SADP) showed that the orientation of the grown CdTe thin films was the (1 0 0) orientation. The lattice constant the strain, and the stress of the CdTe thin film grown on the GaAs substrate were determined from the SADP result. Based on the SADP and HRTEM results, a possible atomic arrangement for the CdTe/GaAs heterostructure is presented.     

Features of FMR spectra observed in granular films formed by Fe+ implantation into PMMA

Magnetic phase consisting of α-Fe particles arranged in a thin near-surface layer has been synthesized in modified phosphorus-containing polymethylmethacrylate by Fe⁺ implantation at an energy of 40 keV with a dose of 1.2⊙10¹⁷ ion/cm². The spectrum of magnetic resonance of the obtained samples is a superposition of a wide anisotropic absorption line and a set of reproducible lowintensity noiselike signals registered in a wide range of magnetic field. It has been established that a wide absorption line is due to particle conglomerates (larger than 200 nm), each behaving as a thin ferromagnetic film. Noiselike lines can be explained as resonance signals from separate oblate/prolate nanoparticles (50–200 nm in size) randomly oriented with respect to the irradiated surface. Such complicated nanostructures can be formed at an appropriate combination of properties of a polymer matrix, types of bombarded ions and implantation regimes.     

磁控溅射Cl掺杂CdTe薄膜的孪晶结构与电学性质

CdTe用作薄膜太阳能电池吸收层需要经过氯处理才能得到高的光电转换效率,其中Cl原子的作用机理仍然没有完全被理解.实验发现Cl原子主要偏聚在CdTe晶界处,对晶界有钝化作用,而有第一性原理计算认为Cl原子掺入CdTe晶格能够引入浅能级提高光电转换效率.为了验证Cl原子掺杂是否对CdTe的光电转换效率有益,本文通过磁控溅射制备了100 ppm(ppm=1/1000000)Cl原子掺杂的CdTe(CdTe:Cl)薄膜并研究了薄膜的晶体结构与电学性质,同时对比了正常氯处理的无掺杂CdTe薄膜与CdTe:Cl薄膜之间的性质区别.实验发现Cl原子掺杂会在CdTe:Cl中形成大量仅由几个原子层构成的孪晶,电子和空穴在CdTe:Cl薄膜中没有分离的传导通道,而在氯处理后的CdTe薄膜中电子沿晶界传导,空穴沿晶粒内部传导.磁控溅射沉积的CdTe:Cl多晶薄膜属于高阻材料,退火前载流子迁移率很低,退火后载流子浓度降低到本征数量级,电阻率提高.CdTe:Cl薄膜电池效率远低于正常氯处理的无掺杂CdTe薄膜电池效率.磁控溅射制备的非平衡重掺杂CdTe:Cl多晶薄膜不适合用作薄膜太阳能电池的吸收层.     

Observation of multiferroic properties in a CdTe:Mn thin film grown by pulsed laser deposition techniques

We report multiferroic properties in a 3% Mn-doped CdTe (CdTe:Mn or CTM) thin film grown in a co-deposition system constituting pulsed laser deposition and radio frequency (RF) sputtering, in which the Mn concentration was tuned by the sputtering rate of Mn. We observed a clear ferroelectric hysteresis loop in the CTM thin film with remanent polarization of 3.5 μC/cm² and ferromagnetism in the film at a temperature lower than the Curie temperature of 15 K. Both features show direct evidence of multiferroics in the CTM thin film.