生长温度对等离子体增强化学气相沉积生长ZnO薄膜质量的影响

以Zn(C2 H5) 2 和CO2 为反应源 ,在低温下用等离子体增强化学气相沉积方法 ,在Si衬底上外延生长了高质量的ZnO薄膜。用X射线衍射谱和光致发光谱研究了衬底温度对ZnO薄膜质量的影响。X射线衍射结果表明 ,在生长温度为2 3 0℃时制备出了高质量 ( 0 0 0 2 )择优取向的ZnO薄膜 ,其半高宽为 0 2 6°。光致发光谱显示出强的紫外自由激子发射与微弱的与氧空位相关的深缺陷发光 ,表明获得了接近化学配比的ZnO薄膜     

衬底温度对PLD法制备ZnO薄膜结构及发光特性的影响

在60Pa的高氧压气氛中,用脉冲激光沉积法以Si(111)为衬底在不同温度下制备了ZnO薄膜.RHEED和XRD结果表明,所有样品都是c轴高度择优取向的多晶ZnO薄膜.随衬底温度的升高,ZnO薄膜(002)衍射峰的半高宽不断减小,从0.227～0.185°.对(002)衍射峰的2θ值分析表明,650℃下生长的ZnO薄膜几乎处于无应力的状态,而在较低或较高温度下生长的薄膜中都存在着一定程度的c轴压应力.室温PL谱测试说明在650℃生长的ZnO薄膜具有最强的紫外发射峰和最窄的UV峰半高宽(83meV).在700℃得到的样品PL谱中,检测到一个位于3.25eV处的低能发射峰.经分析,该峰可能是来自于施主-受主对(DAP)的跃迁.     

Mn掺杂对ZnO薄膜结构和光学性质的影响

利用脉冲激光淀积的方法在Si衬底上生长出了c轴高度取向的ZnO和Zn0.9Mn（0.1）O薄膜.光致发光结果显示了Mn的掺杂引起了薄膜的带边发射蓝移,强度减弱,紫光发射几乎消失,但绿光发射增强.利用X射线衍射,X射线吸收精细结构和X射线光电子能谱等实验技术对Mn掺杂的ZnO薄膜的结构及其对光学性质影响进行了研究.结果表明：Mn掺入到ZnO薄膜中形成了Zn0.9Mn0.1O合金薄膜,Mn以＋2价的价态存在,这就导致了掺Mn以后的薄膜带隙变大,在发光谱中表现为带边发射的蓝移.同时由于掺入的Mn与薄膜中的填隙Zn反应,导致薄膜的结晶性变差,薄膜中的填隙Zn减少,O空位增多,引起带边发射和紫光发射减弱,绿光发射增强.     

6H-SiC单晶表面ZnO薄膜的制备及其结构表征

利用脉冲激光淀积(PLD)技术在6H-SiC单晶衬底上制备了ZnO薄膜. 利用X射线衍射(XRD), 反射式高能电子衍射(RHEED)和同步辐射掠入射X射线衍射(SRGID)φ扫描等实验技术研究了ZnO薄膜的结构. 结果表明:在单晶6H-SiC衬底上制备的ZnO薄膜已经达到单晶水平, 不同入射角的SRGID结果, 显示了ZnO薄膜内部不同深度处a方向的晶格弛豫是不一致的, 从接近衬底界面处到薄膜的中间部分再到薄膜的表面处, a方向的晶格常数分别为0.3264、0.3272和0.3223nm. 通过计算得到ZnO薄膜的泊松比为0.504, ZnO薄膜与单晶6H-SiC衬底在平行于衬底表面a轴方向的实际晶格失配度为5.84%.     

衬底温度对ZnO薄膜生长过程及微观结构的影响研究

以醋酸锌水溶液为前驱体,采用改进的超声喷雾热解法在Si(100)衬底上沉积ZnO薄膜,以X射线衍射(XRD)、扫描电镜(SEM)等手段分析所得ZnO薄膜的晶体结构和微观形貌,着重考察了衬底温度对ZnO薄膜生长过程及微观结构的影响.结果表明,在衬底温度为500℃下所得ZnO薄膜表面均匀光滑,属六方纤锌矿结构,且沿c轴择优生长,晶粒尺寸的为40～50nm;衬底温度对ZnO薄膜生长过程影响显著,随衬底温度的升高,薄膜生长速率存在一极限值,且ZnO薄膜的c轴取向趋势增强,晶粒尺寸得到细化.     

锌膜氧化制备氧化锌薄膜的紫光发射

通过锌膜在金属锌熔点(419℃)以上温度和50Pa的氧气压力下退火氧化的方法制备ZnO薄膜,研究了退火温度对ZnO薄膜组织结构及发光性能的影响.ZnO薄膜的室温光致发光谱是由发光中心在424nm处的单一紫光组成.随着退火温度的升高,紫光的强度增加,当温度超过600℃时紫光的强度反而降低.在50Pa氧气压力下,紫光的发射归因于电子从价带到锌间隙原子(Zni)缺陷之间的跃迁.     

沉积时间对脉冲激光沉积法制备ZnO薄膜性能的影响

采用脉冲激光沉积技术(PLD)在氧气气氛中以高纯Zn为(99.999%)靶材,在单晶硅和石英衬底表面成功生长了ZnO薄膜.通过X射线衍射仪、表明轮廓仪、荧光光谱仪、紫外可见分光光度计对合成薄膜材料的晶体结构、厚度、光学性质等进行了研究,分析了ZnO薄膜的沉积时间对其性能的影响.结果表明,采用PLD法在室温下可以制备出(002)结晶取向和透过率高于75%的ZnO薄膜,但室温下沉积的ZnO薄膜的发射性能较差,沉积时间的延长不能改善薄膜的发光性能.     

脉冲激光沉积(PLD)法生长纳米ZnO薄膜的探索

在Si衬底上用脉冲激光沉积法生长C轴取向高度一致的ZnO纳米薄膜.实验制备ZnO纳米结构,其颗粒尺寸的控制是关键.通过改变衬底温度(400～700℃)和沉积时间,获得不同的ZnO纳米结构.SEM观察,在600℃时颗粒均匀且间隔明显,且该薄膜结构为不连续膜,这与其他衬底温度下所形成的薄膜结构有很大差异.XRD显示,600～700℃结晶良好.     

反应沉积法制备c轴取向ZnO薄膜及表征

以二水合醋酸Zn为原料 ,采用反应沉积方法在非晶玻璃衬底上制备出了高度c轴取向、结晶良好的ZnO薄膜。研究了不同衬底温度和Zn源温度对ZnO薄膜性质的影响 ,探讨了不同衬底温度和Zn源温度下生长ZnO薄膜的最佳参数。本文还讨论了该方法制备ZnO薄膜的沉积机制及优化条件下样品的透光特性。     

衬底温度对磁控溅射制备外延ZnO薄膜结构特性的影响

在不同的衬底温度下,采用磁控溅射方法在蓝宝石(0001)衬底上制备了外延生长的ZnO薄膜.采用原子力显微镜(AFM)、X射线衍射仪(XRD)、可见-紫外分光光度计系统研究了衬底温度对ZnO薄膜微观结构和光学特性的影响.AFM结果表明在不同村底温度制备的ZnO薄膜具有较为均匀的ZnO晶粒,且晶粒的尺寸随衬底温度的增加逐渐增大.XRD结果显示不同温度生长的ZnO薄膜均为外延生长,400℃生长的薄膜具有最好的结晶质量;光学透射谱显示在370nm附近均出现一个较陡的吸收边,表明制备的ZnO薄膜具有较高的质量,其光学能带隙随着衬底温度的增加而减小.     

氧氩比对磁控溅射ZnO薄膜结构及光致发光性能的影响

采用射频反应磁控溅射法以不同的氧氩比在玻璃衬底上制备了ZnO薄膜,并对薄膜进行了退火处理;利用X射线衍射仪（XRD）和原子力显微镜（AFM）分别对薄膜的物相组成和表面形貌进行了分析,利用荧光分光光度计对ZnO薄膜的室温光致发光（PL）谱进行了测试。结果表明：当氧氩气体积比为7∶5时,所制备的ZnO薄膜晶粒细小均匀,薄膜结晶质量最好;ZnO薄膜具有紫光、蓝光和绿光三个发光峰,随着氧氩比的增加,蓝光的发射强度增强,而紫光和绿光的发射强度先增强后减弱,当氧氩气体积比为7∶5时紫光和绿光的发射强度最强。     

Effect of the oxygen partial pressure on the microstructure and optical properties of ZnO:Cu films

Cu-doped zinc oxide (ZnO:Cu) films were deposited on Si substrates using radio frequency reactive magnetron sputtering at different oxygen partial pressures. The effect of oxygen partial pressure on the microstructures and optical properties of ZnO:Cu thin films were systematically investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and fluorescence spectrophotometer. The results indicated that the grain orientation of the films was promoted by appropriate oxygen partial pressures. And with increasing oxygen partial pressure, the compressive stress of the films increased first and then decreased. The photoluminescence (PL) of the samples were measured at room temperature. A violet peak, two blue peaks and a green peak were observed from the PL spectra of the four samples. The origin of these emissions was discussed and the mechanism of violet emission of ZnO:Cu thin films were suggested.     

Co-emission of UV, violet and green photoluminescence of ZnO/TiO2 thin film

ZnO/TiO₂ thin films were fabricated on quartz glass substrates by E-beam evaporation. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectra, optical transmittance and photoluminescence. XRD analysis indicates that the TiO₂ buffer layer can increase the preferential orientation along the (002) plane of the ZnO film. PL measurements suggest that co-emission of strong UV peak at 378 nm, violet peak at 423 nm and weak green luminescence at 544 nm is observed in the ZnO/TiO₂ thin film. The violet luminescence emission at 423 nm is attributed to the interface trap in the ZnO film grain boundaries.     

Properties of ZnO:Al films deposited on polycarbonate substrate

Transparent conducting aluminum-doped zinc oxide (ZnO:Al) films have been prepared on polycarbonate (PC) substrates by pulsed laser deposition technique at low substrate temperature (room-100 °C); Nd-YAG laser with wavelength of 1064 nm was used as laser source. The experiments were performed at various oxygen pressures (3 pa, 5 pa, and 7 Pa). In order to study the influence of the process parameters on the deposited (ZnO:Al) films, X-ray diffraction and atomic force microscopy were applied to characterize the structure and surface morphology of the deposited (ZnO:Al) films. Polycrystalline ZnO:Al films having a preferred orientation with the c-axis perpendicular to the substrate were deposited with a strong single violet emission centering about 377–379 nm without any accompanying deep level emission. The average transmittances exceed 85% in the visible spectrum for 300 nm thick films deposited on polycarbonate.     

Influence of the annealing temperature on violet emission of ZnO films obtained by oxidation of Zn film on quartz glass

The photoluminescence (PL) emission properties of ZnO films obtained on quartz glass substrate by the oxidation of Zn films with the oxygen pressure of 50Pa at temperature of 773 K~973 K were studied. The strong single violet emission centering on 424 nm (or 2.90 eV) without any accompanying deep-level emission and UV emission was observed in the PL spectra of the ZnO films at room temperature. The intensity of violet emission increased with increasing annealing temperature in the range of 773 K~873 K and decreased with increasing annealing temperature in the range of 873 K~973 K. These violet emission bands are attributed to the electron transition from interstitial zinc (Zn_i) level (2.91 eV) to the valence band.     

Annealing effects on the structural and optical properties of growth ZnO thin films fabricated by pulsed laser deposition (PLD)

Annealed ZnO thin film at 300, 350, 400, 450 and 500 °C in air were deposited on glass substrate by using pulsed laser deposition. The effects of annealing temperature on the structural and optical properties of annealed ZnO thin films by grazing incident X-ray diffraction (GIXRD), transmittance spectra, and photoluminescence (PL) were investigated. The GIXRD reveal the presence of hexagonal wurtzite structure of ZnO with preferred orientation (002). The particle size is calculated using Debye–Scherrer equation and the average grain size were found to be in the range 5.22–10.61 ± 0.01 nm. The transmittance spectra demonstrate highly transparent nature of the films in visible region (>70 %). The calculation of optical band gap energy is found to be in the range 2.95–3.32 ± 0.01 eV. The PL spectra shows that the amorphous film gives a UV emission only and the annealed films produce UV, violet, blue and green emissions this indicates that the point defects increased as the amorphous film was annealed.     

Growth and characterization of non-polar ZnO thin films by pulsed laser deposition

Non-polar ZnO thin films were fabricated on r-plane sapphire substrates by pulsed laser deposition at various temperatures from 100 to 500 °C. The effects of the substrate temperature on structural, morphological and optical properties of the films were investigated. Based on the X-ray diffraction analysis, the ZnO thin films grown at 300, 400 and 500 °C exhibited the non-polar (a-plane) orientation and those deposited below 300 °C exhibited polar (c-plane) orientation. In the optical properties of non-polar ZnO films, there were two photoluminescence peaks detected. The peaks (near-band edge emission, blue emission) are due to electron transitions from band-to-band and shallow donor level to valence band, respectively.     

Characterization of pulsed laser deposited zinc oxide

The pulsed laser deposition of zinc oxide films (ZnO) has been studied as a function of laser wavelength, and substrate temperature. Optical emission spectroscopy of the laser produced plume was used to characterize the deposition process. The deposited films were characterized by X-ray diffractometry, Auger electron spectroscopy, and scanning electron microscopy. Highly textured (002) ZnO films deposited at substrate temperatures of 300 °C with laser wavelengths of 532 nm and 248 nm. However, the energy fluence of 248 nm radiation controls the degree of texturing, allowing highly textured films to be deposited at room temperature.     

Influence of incorporation of Al3+ ions on the structural, optical and AC impedance characteristics of spin coated ZnO thin films

Aluminium doped zinc oxide thin films were deposited onto glass substrate using spin coating technique. The effects of Al doping on structural, optical and electrical properties of these films were investigated. X-ray diffraction analysis showed that all the thin films were of polycrystalline hexagonal wurtzite structure with (002) as preferential orientation except 2 at.% of Al doped ZnO films. The optical band gap was found to be 3.25 eV for pure ZnO film. It increases up to 1.5 at.% of Al doping (3.47 eV) and then decreased slightly for the doping level of 2 at.% (3.42 eV). The reason for this widening of the optical band gap up to 1.5 at.% is well described by Burstein–Moss effect. The photoluminescence spectra of the films showed that the blue shift and red shift of violet emission were due to the change in the radiative centre between zinc vacancy and zinc interstitial. Variation in ZnO grain boundary resistance against the doping concentration was observed through AC impedance study.