| 摘要註: |
本研究以化學浴沉積法合成氧化鋅(ZnO)奈米柱陣列,並以熱蒸鍍鍍製不同銅薄膜厚度,分別比較退火前及300℃真空退火之材料,藉由掃描式電子顯微鏡(SEM)觀察材料表面形貌,透過X-ray繞射儀(XRD)得知鍍銅ZnO退火後試片(0002)往高角度偏移,可推測形成主要是Cu2+摻雜於ZnO中,配合穿透式電子顯微鏡(TEM)發現退火前試片ZnO外層披覆著Cu2O及CuO奈米粒子,而退火後試片外層仍殘留Zn摻雜之CuO化合物,由電子繞射圖分析顯示材料屬於單晶奈米柱結構,且由X光光電子能譜儀(XPS)得知退火後試片以Cu2+為主要摻雜離子,此結果與XRD吻合。從陰極發光光譜儀(CL)及光激發光光譜儀(PL)分析結果發現,鍍銅ZnO能隙發光波長偏移量僅1、2 nm,但退火後試片缺陷發光皆有紅移的現象,CL分析之可見光波長位在黃橘光範圍,而PL分析為黃綠光波長範圍,且缺陷發光強度大於能隙發光強度,有潛力應用於可見光發光材料。本研究藉由 n-ZnO/p-CuO 核殼材料之設計,並控制ZnO NRs外層之CuxO厚度,在氣體感測方面利用p/n-type競爭的原理,以提升對氣體感測的選擇性。結果顯示在適當的CuO層厚度下,可以選擇出氨氣體,本研究合成的材料以可見光發光材料及室溫氣體感測之元件的應用具有相當的潛力。 In this study, n-ZnO/p-CuxO core-shell nanorod (NR) and Cu doped ZnO (CZO)arrays were synthesized by depositing CuxO nanoshells with different thickness by thermalcoater on surface of ZnO NRs, prepared by chemical bath deposition, followed byannealing at 300℃ in vacuum for 4 h. Scanning electron microscopy and Transmission electron microscopy showed that theouter CuxO shells were comprised of Cu2O and CuO nanocrystals before annealing. Thecore-ZnO NRs remain a single-crystalline wurtzite structure growing along c-axis evenafter annealing. However, the outer nanoshells transformed to single-crystalline Zn dopedCuO nanoparticles after annealing. X-ray diffraction (XRD) showed the (0002) peaks shiftto higher angle after annealing, indicative of diffusion of Cu and replacement of Zn2+ byCu2+ ions. Cathodoluminescence (CL) and photoluminescence (PL) measurement showthat the wavelength of near-band edge emission of CZO just shift 1-2 nm compared withundoped ZnO. The CZO structures demonstrate strong yellow-orange and green-yellowemissions in CL and PL spectra, respectively. The intensity of defect emissions is muchstronger than near-band edge emission, which shows great potential in fabricatingnanodevices for visible luminescence. In addition, from the gas-sensing measurements at room temperature, then-ZnO/p-CuxO core/shell nanostructures with various CuxO thicknesses demonstrateenhanced selectivity for different gases by utilizing the competition of inner n-ZnO andouter p-CuxO. This work proposes an effective route to synthesize n-ZnO/p-CuxO and CZO nanostructures which have great potential in room-temperature gas sensors andvisible luminescence applications. |