Diffusion and trapping in ZnS:Mn electroluminescent thin films

This paper reports the analysis of a time resolved study concerning both diffusion and trapping in ZnS:Mn TFEL, as a function of the dopant concentration. In particular we show that, above 1%, the excitations most likely diffuse among manganese ions lying on fractal spaces before reaching a trapping center.     

纳米荧光粉的余辉研究

用无机材料在室温下通过溶胶法制成了纳米ZnS:Mn荧光粉,立方晶形,平均粒径为3nm,它的橙色发光（峰值608nm,半宽75nm)亮度与同晶型（立方）的体ZnS:Mn荧光粉的亮度相同,而余辉缩短。在Nd:YAG四倍频266nm脉冲激光激发下,仔细对立方纳米,纯立方微米,纯六角微米ZnS:Mn荧光粉进行了余辉的对比测量,它们的余辉主要遵循指数衰减规律,其1／e余辉时间的结果如下：（1）纯立方纳米ZnS:Mn,两个指数衰减,余辉时间分别为186μs和1078μs,其幅度比为4：1,前者是主要的,决定了1／e余辉时间;（2）纯立方微米体ZnS:Mn:944μs,(3)纯六微米体ZnS:MN:1.2ms（还有幅度很小的极长余辉成分）,结果表明纳米ZnS:Mn荧光粉的光致发光余辉的确比对应的体材料（不管是六角还是立方）都短,但余辉缩短了几倍,而不是五个数量级。     

与掺杂浓度相关的ZnS∶Mn纳米粒子的发光性质

采用溶胶法制备了Mn掺杂的ZnS纳米粒子,探讨了掺杂离子浓度对ZnS∶Mn纳米粒子的晶体结构和发光性质的影响。通过X射线衍射（XRD）对样品的结构进行了表征,结果表明：所制备的ZnS∶Mn纳米粒子为立方闪锌矿结构,其在Mn离子的掺杂浓度达到6%时不发生分相,但随着掺杂浓度的增加,纳米粒子的平均粒径会减小。光致发光光谱和荧光光谱的结果表明：通过改变掺杂离子的浓度可实现对ZnS∶Mn纳米粒子590 nm附近荧光发射波长的调节。此外,研究了温度对纳米粒子形貌和发光性质的影响。高分辨透射电子显微镜（HRTEM）观察发现,经过50℃陈化1 h后的ZnS∶Mn样品的平均粒径增大约为20 nm,且加热陈化有利于ZnS∶Mn纳米粒子中Mn2＋在590 nm处产生荧光。     

Chemical bath-deposited ZnS thin films: Preparation and characterization

Chemical bath deposition of ZnS thin films from NH₃/SC(NH₂)₂/ZnSO₄ solutions has been studied. The effect of various process parameters on the growth and the film quality are presented. The influence on the growth rate of solution composition and the structural, optical properties of the ZnS thin films deposited by this method have been studied. The XRF analysis confirmed that volume of oxygen of the as-deposited film is very high. The XRD analysis of as-deposited films shows that the films are cubic ZnS structure. The XRD analysis of annealed films shows the annealed films are cubic ZnS and ZnO mixture structure. Those results confirmed that the as-deposited films have amorphous Zn(OH)₂. SEM studies of the ZnS thin films grown on various growth phases show that ZnS film formed in the none-film phase is discontinuous. ZnS film formed in quasi-linear phase shows a compact and a granular structure with the grain size about 100 nm. There are adsorbed particles on films formed in the saturation phase. Transmission measurement shows that an optical transmittance is about 90% when the wavelength over 500 nm. The band gap (E_g) value of the deposited film is about 3.51 eV.     

The decay and saturation of the emission in a.c. EL ZnS:Mn thin films

The decay of the yellow emission of a.c. ZnS:Mn electroluminescent cells is faster at high brightness levels. A corresponding quenching of the brightness is seen. This quenching is observed at much lower current densities than would be expected from the Auger coefficient 2X10^-9 cm³ s^-1.     

Electrical breakdown in ZnS:Mn films grown by rf-magnetron sputtering

We have studied the electrical breakdown field strength E_br of ZnS films doped with Mn(ZnS:Mn), produced by rf magnetron sputtering, as a function of film thickness d in the system Al-ZnS:Mn-Al. Electron-microscope studies have shown that breakdown is initiated under inhomogeneous field conditions imposed both by the roughness of the aluminum electrode and by the polycrystallinity of the ZnS:Mn film. An observed increase in E_br as d is reduced below 0.7 µm, with no polarity effect in breakdown under dc field conditions, is explained in terms of an electron-thermal breakdown model.Institute for Automation and Radio Electronics, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 41–44, March, 1993.     

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.     

金属离子表面修饰对纳米ZnS:Mn2+溶胶发光性质的影响

利用胶体化学共沉淀方法制备了纳米ZnS：Mn^2 乙醇溶胶,观察到Zn^2 的引入对内部Mn^2 的^4T1→^6A1跃迁的580nm橙色发光有激活作用,而外加的Mn^2 对该橙色发光有猝灭作用。Zn^2 的吸附通过形成单层ZnS壳,减少了表面猝灭中心,从而使发光强度增加,这种表面猝灭中心最有可能是来自表面S^2-孤对电子的悬空键。Mn^2 的猝灭过程不能用纯粹动态的猝灭过程来描述,Mn^2 本身很可能就是橙光的猝灭中心。考虑到Mn^2 在颗粒表面上的按泊松分布,并假设单个Mn^2 能100％猝灭Mn^2 580nm发射,理论与实验数据很好地符合。通过对猝灭数据的拟合,估算出的颗粒尺寸小于用有效质量近似模型算得的3．1nm,分析了可能的原因。     

Structural and morphological characterization of CdSe:Mn thin films

The nonlinear propagation of cylindrical and spherical dust-ion-acoustic (DIA) envelope solitary waves in unmagnetized dusty plasma consisting of dust particles with opposite polarity and non-extensive distribution of electron is investigated. By using the reductive perturbation method, the modified nonlinear Schrödinger (NLS) equation in cylindrical and spherical geometry is obtained. The modulational instability (MI) of DIA waves governed by the NLS equation is also presented. The effects of different ranges of the non-extensive parameter q on the MI are studied. The growth rate of the MI is also given for different values of q. It is found that the basic features of the DIA waves are significantly modified by non-extensive electron distribution, polarity of the net dust-charge number density and non-planar geometry.     

Laser phenomena in DCEL of ZnS:Cu:Nd:Cl thin films

The possibility of the occurrence of laser phenomena in the DCEL of thin films of ZnS:Cu:Nd:Cl, designed for display purposes, has been investigated. Evidence of stimulated emission at ～ 1080 nm has been found in both DCEL and cathodoluminescence emission of the films and has been attributed to a tendency to population inversion involving the ${}^4\text{F}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}$ energy level and a sub-level of the ${}^4\text{I}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ energy level. In addition, the expected directional nature of the stimulated emission has been shown to be present at the higher applied voltages.     

Local atomic structure around Mn ions in GaN:Mn thin films: Quantitative XANES analysis

GaN:Mn dilute magnetic semiconductors with zinc-blende type of lattice and room temperature ferromagnetism were investigated by the X-ray absorption near edge structure (XANES) with a high accuracy approach of the multidimensional interpolation, which makes it possible to determine the nanoscale local atomic structure around Mn impurities. It is found that Mn atoms are substantially incorporated into the GaN lattice and Jahn-Teller distortion around Mn atom is observed. Our results show that symmetry changes around Mn atom influence on XANES spectrum significantly. Furthermore, the possible impact of local distortions on the magnetic properties is discussed.     

变色的ZnS：Mn/SrS：Ce/ZnS：Mn薄膜电致发光的研究

利用ZnS:Mn/SrS:Ce/ZnS:Mn多层结构,得到了一种可变颜色的薄膜电致发光器件。研究了这一器件的发射光谱随电压和频率的变化,并讨论了随电压的增加,发射光谱中蓝带和黄带的不同增长的原因,以及在不同电压下,发射光谱中蓝带和黄带随频率变化的不同趋势的原因。观察到随驱动频率的增加,发射光谱出现黄-蓝色位移。     

多晶Si0.9654Mn0.0346:B薄膜的磁性研究

利用磁控溅射和快速热处理的方法制备了Mn,B共掺的多晶硅薄膜(Si0.9654Mn0.0346:B).磁性和结构研究发现薄膜有两个铁磁相.低温铁磁相来源于杂相Mn4Si7,高温铁磁相(居里温度TC～250K)是由Mn原子掺杂进入Si晶格导致.晶化后的薄膜利用射频等离子体增强化学气相沉积系统(PECVD)进行短暂(4min)的氢化处理后发现,薄膜的微结构没有发生变化而饱和磁化强度却随着载流子浓度的增大而增大.样品的饱和磁化强度和载流子浓度密切相关为验证在硅基磁半导体中磁性是以空穴为媒介的这一理论提供了有力的证据.     

Room-temperature ferromagnetism in N+-implanted ZnO:Mn thin films

Mn–N co-doped ZnO films with wurtzite structure were fabricated by RF magnetron sputtering together with the ion-implantation technique. Then a post-annealing at 650 °C for 10 min in a N₂ atmosphere was performed to activate the implanted N⁺ ions and recover the crystal quality, and a p-type ZnO:Mn–N film with a hole concentration of about 2.1×10¹⁶ cm^?3 was obtained. It is found that the Mn mono-doped ZnO film only exhibits paramagnetic behavior, while after N⁺-implantation, it shows ferromagnetism at 300 K, and the magnetization of the ZnO:Mn–N films can be further enhanced by thermal annealing due to the activation of the N acceptors. Our experimental results confirm that the codoping N acceptors are favorable for ferromagnetic ordering of Mn²⁺ ions in ZnO, which is consistent with the recent theoretical calculations.     

Influence of low-temperature sulfidation on the structure of ZnS thin films

ZnS thin films were prepared by sulfuring zinc thin films at different sulfuration temperatures. The crystal structure,surface morphology, defects, and optical properties of the thin films were characterized by x-ray diffraction(XRD), scanning electron microscopy(SEM), positron annihilation Doppler broadening, and UV-Vis spectrophotometer, respectively.It was found that the(200)-plane preferred orientation of the ZnS thin films changed to(111)-plane with increasing sulfidation temperature. Moreover, a number of large holes were generated at 420?C and eliminated at 440?C. The concentration of defects was lowest when the sulfuration temperature was 440?C. The optical transmission of all samples was maintained at 60%–80% in the wavelength range of 400 nm–800 nm, and the band energy of the ZnS thin films was approximately3.5 e V for all treatment temperatures except 430?C.