| 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. |
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