【作者】 王昊午；

【导师】 张伟风；

【作者基本信息】 河南大学 ， 微电子学与固体电子学， 2012， 硕士

【摘要】 ZnO是II-VI族直接宽禁带化合物半导体材料，在400nm-2μm波长范围内有很高的透光率，是一种新型的透明半导体材料。另外，ZnO还具有成本低，无毒性，资源丰富，热稳定性高和容易合成等众多优点而成为制备光电器件的优良材料，具有很高的开发潜力和应用前景。另一方面，还具有丰富的纳米结构，包括纳米线、纳米管、纳米带、纳米棒等使人们对它保持着浓厚的兴趣。因此，纳米氧化锌作为一种新型功能材料在场效应晶体管、肖特基二极管、紫外光探测器、气敏传感器、纳米发电机等领域有良好的应用及发展前景。本文以ZnO为基础与金属Cu和Se粉制备了ZnO/Cu、ZnO/Cu/ZnO多层透明导电薄膜和ZnO:Se纳米颗粒。研究了不同Cu层溅射时间对透明导电薄膜性能的影响，另外也通过表面光电压研究了ZnO:Se纳米粒子的光电特性，本论文的主要内容如下：1选纯度99.99%的ZnO粉末和自制稀粘合溶剂作为原料，采用合理的烧结工艺在空气气氛下制备出优良的ZnO陶瓷靶材。由XRD图谱可得制备出的ZnO陶瓷靶材与ZnO粉体物相一致均为多晶的六角纤锌矿结构，结晶良好，没有产生其它杂相。2采用射频磁控溅射技术，以高纯度ZnO为靶材，在高纯Ar环境，气体压强设定1.0Pa，固定靶和衬底的距离为65mm，溅射功率为80W的条件下在玻璃衬底上制备了ZnO薄膜。研究了不同溅射时间对ZnO薄膜光学透光率的影响。从透射图可得5min溅射的ZnO薄膜的透光率均在90％以上，10min溅射的ZnO薄膜的透光率基本上在85％以上，而15min溅射的ZnO薄膜出现最低的透光率基本上在70％以上，这主要是溅射时间的增加，薄膜的厚度增加，越来越多的光子被材料吸收，导致平均透光率呈下降趋势。说明溅射时间对薄膜的光学特性影响很大。3以ZnO陶瓷靶和金属Cu靶为基础在室温条件下利用直流磁控溅射和射频磁控溅射技术在玻璃衬底上制备了ZnO/Cu多层透明导电薄膜。通过改变金属Cu层的溅射时间，并采用紫外-可见-近红外（UV-Vis-NIR）分光光度计和霍尔测试仪对ZnO/Cu多层薄膜的光学性质、电学性质等进行了研究和分析。对ZnO多层透明导电薄膜而言，金属层的溅射时间是一个很大的影响因素。多层透明导电薄膜的导电性能随金属溅射时间的增加而增强，然而，随着金属层溅射时间的增加多层薄膜的透光性将显著降低。这是因为ZnO和金属Cu的功函数相差比较大，金属与半导体接触时将发生载流子的流动。由于ZnO的功函数明显大于金属Cu的功函数，电子将从功函数小的Cu层跑到功函数大的半导体ZnO层中，导致半导体ZnO层载流子浓度增加，电阻率降低。电子在传输中要经过晶界，很容易受晶界的散射作用，由于Cu层溅射时间比较短，Cu层会很容易形成岛状结构，导致不连续的散射增加，使薄膜的迁移率降低。当Cu层沉积时间变长时，Cu层开始变连续岛状结构减小，大部分电流经过低阻的Cu层，薄膜的迁移率载流子浓度增加，电阻率降低。从薄膜的透射谱中发现，Cu层的引入降低了多层薄膜的透光率，这主要是因为随着Cu层溅射时间的增加，更多的电子参与了跃迁而吸收更多的光，使多层结构薄膜的透光率随溅射时间的增加而降低。随着多层结构薄膜载流子浓度的增加薄膜的光学带隙Eg下降。4本节我们在室温条件下利用直流磁控溅射和射频磁控溅射技术在玻璃衬底上制备了ZnO与Cu层相结合的ZnO/Cu/ZnO多层结构薄膜，通过改变ZnO层的溅射功率和金属Cu层的溅射时间等工艺参数，并采用紫外-可见-近红外（UV-Vis-NIR）分光光度计和霍尔测试仪对ZnO/Cu/ZnO多层薄膜的光学性质、电学性质等进行了研究和分析。当Cu层的溅射时间增加时薄膜的载流子浓度提高，霍尔迁移率先降低后随着时间的增加再上升，薄膜的电阻率降低。相同的Cu层不同ZnO溅射功率对薄膜的电学性质影响不大，对薄膜的透过率有比较大的影响。5以醋酸锌和Se粉为原料,以乙二胺为溶剂,利用溶剂热和固相合成法制备了Se掺氧化锌(ZnO:Se)纳米颗粒,并通过X射线衍射、扫描电镜、拉曼散射、紫外可见光吸收、表面光电压等手段对样品进行表征测试，并通过表面光电压谱来初步评估纳米颗粒的光电性能．所合成ZnO:Se的表面光电压谱显示出两个光电响应带，即在330-380nm之间能观察到一个明显的光电响应带，同时在380-395nm又出现了第二个新的相对较弱的光电响应带，直至500nm。在正偏压下，ZnO:Se纳米材料的电场诱导表面光电压谱的光电强度明显变弱。ZnO:Se纳米材料的电场诱导的表面光电谱显现了两个光电响应带在加正压时不同的变化，即与第二个光电响应带对比，正向偏压对第一个光电响应带的SPS强度有更加显著的减弱作用。引入Se杂质能级对上述现象进行了不同的解释。更多还原

【Abstract】 ZnO is a II-VI group multifunctional material with wide direct band-gap and high transmitssion in therange of wavelengths (400nm-2μm). In addition, ZnO is an excellent material to prepare photoelectricdevices due to its advantages, such as low cost, low toxicity，rich resource, good thermal stability, and easyfabrication. On the other hand, zinc oxide based on naostructures including nanowires, nanotubes,nanobelts and nanorods have attracted increasing interest. ZnO nanostructures also exhibits a range ofremarkable potential applications in fuctional devices such as Field-Effect-Transistor, Schottky diode,UV-optical detector, Gas sensor and Nanogenerator, which have profound impacts in future development.ZnO/Cu and ZnO/Cu/ZnO multilayer transparent conductive thin film and ZnO: Se nanoparticleswere prepared based on ZnO with Cu and Se powders, and investigated the influence of with differentsputtering time of copper layers for the transparent conductive thin film and photoelectric properties ofZnO: Se nanoparticles by surface photovoltage spectroscopy. The significant results are listed as follows:1. ZnO ceramic targets were prepared with ZnO powder with the purity of99.99%, deionized water of18.2M and PVA as primary material and by calcining the precursor in air atmosphere at the righttemperature. The X-ray diffraction (XRD) pattern of the as-prepared ceramic targets had good crystallinityand exhibited a single phase of ZnO wurtzite structure, which was similar to ZnO powder. And nocharacteristic diffraction peak was observed according to the XRD pattern.2. Sputtering was carried out at a working gas pressure of1.0Pa in pure argon gas (purity99.999%)and with a RF power of80W based on a oxide ceramic disk of ZnO targets. The glass was used as asubstrate material, with a target–substrate distance of65mm. The transmission properties of the ZnO films are also investigated to understand the influence of with different sputtering time of the ZnO films. Whenthe deposition time is5min, the optical transmittance of ZnO films is about90%over the visible range ofwavelengths. When the deposition time is from10min to15min, the average transmittance of the ZnOfilms drops from85%to70%. The decrease of the average transmittance in visible range can be ascribed toabsorption by the ZnO films, when the film thickness increases because of increasing sputtering time of theZnO films. The results indicate the sputtering time of the ZnO films plays an important role in determiningthe optical properties of the ZnO film.3. ZnO/Cu multilayers were prepared on glass substrates by RF magnetron sputtering of ZnO and DCmagnetron sputtering of Cu at room temperature based on a oxide ceramic disk of ZnO and metal Cutargets. We change the sputtering time of copper layer, and use UV-VIS spectrometer and Hall EffectMeasurement System to measure characteristics such as optical properties, electrical properties. Thesputtering time of metal layer plays an important role in determining the photoelectric property of the ZnOmultilayer structure films. As the sputtering time of copper layer increases, the electrical properties ofZnO/Cu multilayers films were improved greatly by introducing a Cu layer. However, the sputtering timeof Cu films affect the optical properties in the visible wavelength region such as reduced transmittance.When thin film layers of ZnO and Cu were deposited on glass substrates at room temperature, the Cu/ZnOcontacts were fabricated. With the work function difference being large, there is significant injection ofcarriers into the ZnO layer. This can be seen in the substantial increase in conductivity of the multilayerstructure and a small rise in carrier concentration even with short time for sputtering Cu film. However, atthis short time for sputtering Cu, the ZnO/Cu structure has lesser mobility than the ZnO film, because thecurrent passes through the amorphous ZnO layer with the Cu islands acting as discontinuous scatering sitesreducing the mobility further. As the sputtering time of copper layer increases further, the layer becomes near-continuous and the carrier concentration increases with increasing the sputtering time of Cu layer. Asignificant amount of current starts to pass through the low resistivity Cu layer. The mobility and the carrierconcentration increases further because the copper layer becomes continuous. The decrease in resistivity isa consequence of changes in carrier concentration and mobility. Multilayer films introduced a Cu layerfrom the transmission spectrum decline rapidly with sputtering time of the copper layer extending and showa decrease in the average transmittance since photons are strongly absorbed in terms of photon’s transitionsby the high density of charge carriers. The band gap Egof the multilayer structure films decreased withincreasing carrier concentration of the films.4. ZnO/Cu/ZnO multilayers were prepared on glass substrates by RF magnetron sputtering of ZnO andDC magnetron sputtering of Cu at room temperature based on a oxide ceramic disk of ZnO and metal Cutargets. We change the sputtering time of copper layer and the RF power of ZnO layer, and use UV-VISspectrometer and Hall Effect Measurement System to measure characteristics such as optical properties,electrical properties. The carrier concentration increases and the mobility shows a first decrease and thenincrease with increasing the sputtering time of copper layer. The decrease in resistivity is a consequence ofchanges in carrier concentration and mobility. As the same sputtering time of copper layer, the electricalproperties of ZnO/Cu/ZnO multilayers films are little correlated with the RF power of ZnO layer, however,the transmittance of the multilayer structure films are deeply correlated.5. ZnO incorporated selenium nanoparticles have been synthesized by combining solvothermalprocess and solid phase recrystallization method based on Zinc acetate Dihydrate and selenium powder.The as-prepared samples were also characterized by the techniques such as XRD, SEM, Raman,UV-visible absorption spectroscopy, surface photovoltage spectroscopy (SPS) and electric-field inducedsurface photovoltage spectroscopy (EFISPS), and their Photoelectric properties was evaluated by the surface photovoltage spectroscopy. The SPS response shows two response peaks at approximately366nmand385nm, extending the SPS response toward500nm. The intensity of FISPS signal of ZnO:Senanoparticles decreases as the positive bias increases. The FISPS indicates that the intensity of SPS signalof the response peaks at approximately366nm decreases more remarkably than the response peak atapproximately385nm as the positive bias increases. Based on the SPS spectrum, we used the Se-inducedimpurity band model to analyze the photoelectric properties.更多还原