Cu掺杂氧化锌薄膜的发光特性研究

通过射频反应溅射法在Si（111）衬底上制备了不同Cu掺杂量的ZnO薄膜.室温下测量了样品的光致发光（PL）谱，所有样品的PL谱中均观察到435?nm左右的蓝光发光带，该发光带的强度与Cu掺杂量和溅射功率有关.当溅射功率为150?W，Cu掺杂量为2.5%时，ZnO薄膜的PL谱中出现了较强的蓝光双峰，而溅射功率为100?W，Cu掺杂量为1.5%时，出现了位于437nm（2.84eV）处较强的蓝光峰，后者的取向性较好.还研究了掺杂量和溅射功率对发光特性的影响，并对样品的蓝光发光机制进行了探讨. 关键词： ZnO薄膜 Cu掺杂 光致发光谱 射频反应共溅射     

Structural and photoluminescent properties of ZnO films deposited by radio frequency reactive sputtering

Zinc oxide films with c-axis preferred orientation were deposited on silicon (100) substrates by radio frequency (RF) reactive sputtering. The properties of the sam- ples were characterized by X-ray diffractometer, X-ray photoelectron spectroscopy and fluorescent-spectrophotometer. The effect of sputtering power and substrate temperature on the structural and photoluminescent (PL) properties of the ZnO films was investigated. The results indicated that when the sputtering power is 100 W and the substrate temperature is 300-400℃, it is suitable for the growth of high c-axis orientation and small strain ZnO films. A violet peak at about 380 nm and a blue band at about 430 nm were observed in the room temperature photolumines- cence spectra, and the origin of blue emission was investigated.     

Influence of excitation light wavelength on the photoluminescence properties for ZnO films prepared by magnetron sputtering

Highly orientated polycrystalline ZnO films were deposited on sapphire, silicon and quartz substrates at room temperature by r.f. magnetron sputtering. Different photoluminescence (PL) spectra were observed when excited with different wavelength light. A UV emission peak (356 nm) and a blue peak (446 nm) were generated for the films on sapphire, silicon and quartz substrates, and only the 446 nm blue emission appeared for the films on glass substrates when the wavelength of the excitation light was 270 nm. With increasing the wavelength of the excitation light up to 300 and 320 nm, the UV emission disappeared for films on various substrates and the wavelength of the PL peaks increased up to 488 and 516 nm, respectively. When the wavelength of the excitation light increased to 398 nm, the PL spectrum becomes a wide band that is consistent with three emission peaks.     

Preparation of transparent conductive ZnO:Tb films and their photoluminescence properties

Tb-doped Zinc oxide (ZnO:Tb) films were prepared by RF reactive magnetron sputtering of a Zn target with some Tb-chips attached. The results show that the appropriate Tb ions incorporated into ZnO films can improve the structural and electrical properties of ZnO films. Photoluminescence (PL) measurements show that the characteristic emission lines correspond to the intra-4f^n-shell transitions in Tb^{3+} ions at room temperature. Under the optimal conditions, the ZnO:Tb films were prepared with the lowest resistivity (ρ) of 9.34×10^{ -4}Ωcm, transmittance over 80% at the visible region and the strong blue emission.     

ZnO薄膜的制备和结构特性及应变

在SiO₂/Si衬底上面,利用射频磁控溅射方法,在不同的工艺条件下生长ZnO薄膜,然后进行热处理(600～1000℃退火).研究了氩氧比和退火温度对薄膜结晶性能的影响.薄膜的表面结构和晶体特性通过扫描电子显微镜(SEM)、X射线衍射(XRD)来进行表征.结果表明:所制备的薄膜为多晶纤锌矿结构,具有垂直于衬底的c轴(002)方向的择优取向性.热处理可使ZnO(002)衍射峰相对强度增强,半峰全宽(FWHM)变小,即退火使c轴生长的薄膜取向性增强.未经退火的ZnO薄膜存在张应力,经过热处理后应力发生改变,最后变成压应力,并且随着退火温度的升高,压应力逐渐增大.     

Structural and optical properties of Mn-doped ZnO nanocrystalline thin films with the different dopant concentrations

The transparent nanocrystalline thin films of undoped zinc oxide and Mn-doped (Zn_1−xMn_xO) have been deposited on glass substrates via the sol–gel technique using zinc acetate dehydrate and manganese chloride as precursor. The as-deposited films with the different manganese compositions in the range of 2.5–20 at% were pre-heated at 100 °C for 1 h and 200 °C for 2 h, respectively, and then crystallized in air at 560 °C for 2 h. The structural properties and morphologies of the undoped and doped ZnO thin films have been investigated. X-ray diffraction (XRD) spectra, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were used to examine the morphology and microstructure of the thin films. Optical properties of the thin films were determined by photoluminescence (PL) and UV/Vis spectroscopy. The analyzed results indicates that the obtained films are of good crystal quality and have smooth surfaces, which have a pure hexagonal wurtzite ZnO structure without any Mn related phases. Room temperature photoluminescence is observed for the ZnO and Mn-doped ZnO thin films.     

Effects of Ti-doped concentration on the microstructures and optical properties of ZnO thin films

The Ti-doped ZnO (ZnO:Ti) thin films have been deposited on glass substrates by radio frequency (RF) reactive magnetron sputtering technique with different Ti doping concentrations. The effect of Ti contents on the crystalline structure and optical properties of the as-deposited ZnO:Ti films was systematically investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and fluorescence spectrophotometer. The XRD measurements revealed that all the films had hexagonal wurtzite type structure with a strong (100) preferential orientation and relatively weak (002), (101), and (110) peaks. It was found that the intensity of the (100) diffraction peaks was strongly dependent on the Ti doping concentration. And the full width at half-maximum (FWHM) of (002) diffraction peaks constantly changed at various Ti contents, which decreased first and then increased, reaching a minimum of about 0.378° at 1.43 at.% Ti. The morphologies of ZnO:Ti films with 1.43 at.% Ti showed a denser texture and better smooth surface. All the films were found to be highly transparent in the visible wavelength region with an average transmittance over 90%. Compared with E_g = 3.219 eV for pure ZnO film, all the doping samples exhibited a blue-shift of E_g. It can be attributed to the incorporation of Ti atoms and raising the concentration of carriers. Five emission peaks located at 412, 448, 486, 520, and 550 nm were observed from the photoluminescence spectra measured at room temperature and the origin of these emissions was discussed.     

The structure and magnetic properties of Cu-doped ZnO prepared by sol-gel method

The Cu-doped ZnO and pure ZnO powders were synthesized by sol-gel method. The structural properties of the samples were investigated by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. All the results confirmed that copper ions were well incorporated into the ZnO lattices by substituting Zn sites without changing the wurtzite structure and no secondary phase existed in Cu-doped ZnO nanoparticles. The Zn_0.97Cu_0.03O nanoparticles exhibited ferromagnetism at room temperature, as established by the vibrating sample magnetometer analysis.     

Effects of the substrate and oxygen partial pressure on the microstructures and optical properties of Ti-doped ZnO thin films

Ti-doped ZnO (ZnO:Ti) thin films were deposited on the glass and Si substrates using radio frequency reactive magnetron sputtering. The effects of substrate on the microstructures and optical properties of ZnO:Ti thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a fluorescence spectrophotometer. The structural analyses of the films indicated that they were polycrystalline and had a hexagonal wurtzite structure on different substrates. When ZnO:Ti thin film was deposited on Si substrate, the film had a c-axis preferred orientation, while preferred orientation of ZnO:Ti thin film deposited on glass substrate changed towards (1 0 0). Finally, we discussed the influence of the oxygen partial pressures on the structural and optical properties of glass-substrate ZnO:Ti thin films. At a high ratio of O₂:Ar of 18:10 sccm, the intensity of (0 0 2) diffraction peak was stronger than that of (1 0 0) diffraction peak, which indicated that preferred orientation changed with the increase of O₂:Ar ratios. The average optical transmittance with over 93% in the visible range was obtained independent of the O₂:Ar ratio. The photoluminescence (PL) spectra measured at room temperature revealed four main emission peaks located at 428, 444, 476 and 527 nm. Intense blue-green luminescence was obtained from the sample deposited at a ratio of O₂:Ar of 14:10 sccm. The results showed that the oxygen partial pressures had an important influence for PL spectra and the origin of these emissions was discussed.     

Cu掺杂ZnO薄膜的光学性质

采用射频反应磁控溅射方法,在Si(100)和石英基片上使用双靶溅射的方法制备了Cu掺杂ZnO薄膜。利用X射线衍射、透射光谱和光致发光光谱分析了薄膜的晶体结构及光学性质,并与密度泛函理论计算的结果进行了对比。研究结果显示:Cu掺杂ZnO薄膜均具有高的c轴择优取向,无Cu及其氧化物相关相析出,掺杂对晶格参数的影响较小,与理论计算结果一致。Cu掺杂显著改变了ZnO薄膜在近紫外及可见光波段的吸收特性,其光学带隙随着Cu掺杂量的增加有所减小,带隙宽度的变化趋势与理论结果有着很好的一致性。Cu掺杂显著降低了ZnO薄膜的发光效率,具有明显的发光猝灭作用,但并不影响光致发光的发光峰位。说明Cu掺杂导致的吸收特性的改变可能与杂质能级有关,这与能带结构计算发现的Cu-3d电子态位于价带顶附近的禁带中是一致的。     

Structural,optical,and electrical properties of Cu-doped ZrO_2 films prepared by magnetron co-sputtering

Copper(Cu)-doped ZrO_2(CZO) films with different Cu content(0 at.%～ 8.07 at.%) are successfully deposited on Si(100) substrates by direct current(DC) and radio frequency(RF) magnetron co-sputtering. The influences of Cu content on structural, morphological, optical and electrical properties of CZO films are discussed in detail. The CZO films exhibit ZrO_2 monocline(ˉ111) preferred orientation, which indicates that Cu atoms are doped in ZrO_2 host lattice. The crystallite size estimated form x-ray diffraction(XRD) increases by Cu doping, which accords with the result observed from the scanning electron microscope(SEM). The electrical resistivity decreases from 2.63 ?.cm to 1.48 ?·cm with Cu doping content increasing, which indicates that the conductivity of CZO film is improved. However, the visible light transmittances decrease slightly by Cu doping and the optical band gap values decrease from 4.64 eV to 4.48 eV for CZO films.     

Enhancement of surface morphology and optical properties of nanocolumnar ZnO films

Nanocolumnar ZnO films were prepared by electrodeposition (ED) on a glass substrate covered with a conductive layer of thin oxide doped with fluorine (FTO). After deposition the samples were annealed in oxidizing or reducing atmosphere, at temperatures between 100 to 500 C, in order to follow the evolution of optical properties and morphology. The optical properties of these films were studied by means of photoluminescence spectroscopy (PL) and the morphology by scanning electron microscopy (SEM). Films annealed at 300 C exhibit a higher ultraviolet emission peak, originating from exciton transitions. A green band related to deep-level emission centered at 500 nm, shows a drastic increase at 500 C. These results are independent of the annealing atmosphere. An increase of coalescence is also observed after annealing at 500 C. These results are explained taking into account the contribution of different point defects.     

Au层退火温度对ZnO/Au/ZnO多层膜的结构、光学及电学性质的影响

采用金属有机化学气相沉积(MOCVD)技术在蓝宝石衬底上制备出晶体质量较好的透明导电的ZnO/Au/ZnO(ZAZ)多层膜,其中,Au夹层是通过射频磁控溅射的方法获得。通过对Au夹层进行不同温度的退火处理,研究了Au层退火温度对ZAZ多层膜的结构特性、电学性能和光学特性的影响。利用原子力显微镜(AFM)、扫描电子显微镜(SEM)、X射线衍射(XRD)仪、霍尔效应测试和透射谱分析等测试手段对ZAZ多层膜的性质进行了分析。测试结果表明,在200 ℃下对Au夹层进行快速退火处理,多层膜的结构、电学和光学性质达到最优,表面等离子体效应也更明显。其中,XRD(002)衍射峰的半高宽为0.14°,电阻率为2.7×10^-3 Ω·cm,载流子浓度为1.07×10²⁰ cm^-3,可见光区平均透过率为75.3%。     

Thickness effect on the evolution of morphology and optical properties of ZnO films

N-Al co-doped ZnO films with various thicknesses were deposited on glass substrates by ultrasonic spray pyrolysis (USP). The crystalline microstructure, morphology, distribution of elements and photoluminescence properties of ZnO films were characterized by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and photoluminescence (PL) spectroscopy. The XRD and FESEM results show that with the increase of film thickness the grain size increases and the grain shape changes from regular hexagonal sheet-like to wedge-shaped, even pyramidal. The PL spectra illustrate that there is an obvious red-shift for the emission center from ultraviolet to blue region, and the intensities of defects emissions increase with the increase of thickness. In addition, the electrical properties are proved to be strongly affected by film thickness.     

Spectral features and antibacterial properties of Cu-doped ZnO nanoparticles prepared by sol-gel method

Zn_(1-x)Cu_x O(x=0.00, 0.01, 0.03, and 0.05) nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%(x = 0.05). However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli(Gram negative bacteria)cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.     

Effect of Ag doping on the photoluminescence properties of ZnO films

ZnO:Ag films were grown on Si (1 0 0) substrates by ultrasonic spray pyrolysis at various substrate temperatures. The effect of deposition temperature on the structural and the room temperature photoluminescence (RT-PL) properties of ZnO:Ag films was studied. With the deposition temperature rising to 550 °C, the intensity of the near-band edge (NBE) emission at 378 nm decreased and a new emission peak at 399 nm was observed. On the basis of the X-ray diffraction pattern (XRD), the X-ray photoelectron (XPS) spectra of ZnO:Ag films, and the effects of annealing on the PL, we suggest that the 399 nm emission should be attributed to the electron transition from the conduction band to Ag_Zn-related complexes defects radiative centers above the valence band.     

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     

退火温度对ZnO薄膜结构和发光特性的影响

采用反应射频磁控溅射法在 Si(100)基片上制备了高c轴择优取向的ZnO薄膜，研究了退火温度对ZnO薄膜的晶粒尺度、应力状态、成分和发光光谱的影响，探讨了ZnO薄膜的紫外发光光谱和可见发光光谱与薄膜的微观状态之间的关系.研究结果显示,在600—1000℃退火温度范围内，退火对薄膜的织构取向的影响较小，但薄膜的应力状态和成分有比较明显的变化.室温下光致发光光谱分析发现，薄膜的近紫外光谱特征与薄膜的晶粒尺度和缺陷状态之间存在着明显的对应关系；而近紫外光谱随退火温度升高所呈现的整体峰位红移是各激子峰相对比例变 关键词： ZnO薄膜 退火 光致发光 射频反应磁控溅射 可见光发射     

Structural and optical properties of ZnO thin films on (111) CaF2 substrates grown by magnetron sputtering

ZnO thin films were grown on (111) CaF₂ substrates by magnetron sputtering at room temperature. Structural and optical properties of the ZnO thin films were studied. XRD analysis showed that the ZnO thin films had the (002) preferential orientation. The transmittance of ZnO thin films was over 80% in the visible range. The optical band gap of the ZnO thin films was 3.26 eV. The optical constants (n,k)$(n,k)$ of the ZnO thin films in the wavelength range 300–1000 nm were obtained by infrared spectroscopic ellipsometry measurement. PL spectra of ZnO thin films showed strong UV near-band-edge emission peak at 376.5 nm and weak visible red emission at 643.49 nm using He–Cd laser as the light source, using a synchrotron radiation light source PL spectra showed three emission peak at 320 nm, 410 nm and 542 nm respectively.