【作者】 张晓利；

【导师】 刘昌龙；

【作者基本信息】 天津大学 ， 材料物理与化学， 2010， 硕士

【摘要】 通过室温磁控溅射方法在玻璃基底上制备了厚度为300 nm的氧化锌薄膜,采用离子注入技术在ZnO薄膜中顺次注入Fe和C离子,Fe离子注入能量和注入剂量分别为120 keV和5×10¹⁶ cm^-2,C离子注入能量为20 keV,剂量分别为1×10¹⁵、3×10¹⁵和5×10¹⁵ cm^-2。部分注入后的ZnO样品在氧气气氛下进行退火,退火温度为350℃,时间为两个小时。借助于扫描电子显微镜（SEM）、X射线衍射谱仪（XRD）、X射线光电子能谱仪（XPS）、紫外-可见吸收（谱仪UV-Vis）、光致发光谱仪（PL）和物理性能测试系统（PPMS）对注入及退火的ZnO样品的形貌、结构、成分、光学性质和磁学性质进行了测试和分析。通过研究获得了以下主要结果:（1） SEM和EDX测试结果表明,Fe和C离子的顺次注入会使得ZnO样品表面变得粗糙,氧气氛围下350℃退火处理促进了ZnO晶粒的生长。双注入及退火导致ZnO表面主要元素成分的含量都有所下降。（2）结构测试分析结果表明,制备态的ZnO薄膜主要呈现两个衍射峰,即ZnO（002）和（004）衍射峰,在Fe离子单注入ZnO薄膜出现了Fe的衍射峰,即α-Fe（110）衍射峰,表明在Fe注入的ZnO薄膜中产生了Fe的纳米颗粒。随后的C离子注入会明显地破坏Fe的纳米颗粒,导致随着C离子注入剂量的增大,α-Fe（110）的峰变弱,并且在63°附近开始出现很小的衍射峰,标志Fe纳米颗粒发生了氧化作用。不仅如此,通过对ZnO（002）峰的详细分析,结果显示Fe和C双注入在ZnO薄膜中引入的大量的晶格缺陷,使得（002）衍射峰强度明显变低,ZnO纳米颗粒也相应的变大。观测到了ZnO（002）衍射峰在注入条件下均发生红移。（3）XPS测试结果显示注入Fe原子在样品中主要以两种价态存在,即Fe的零价态和化合价态。C注入ZnO薄膜后取代O的位置,并与Zn键合,形成Zn-C键。（4）光学性质表征结果显示ZnO薄膜在380 nm附近出现很强的吸收,Fe单注入使的ZnO薄膜的光学带隙变小,而附加的C离子的注入则会导致其光学带隙增大。通过对各条件下的ZnO薄膜进行发光谱测试,结果表明Fe离子注入会使得ZnO薄膜样品的发光增强,而Fe和C离子双注入下反而使得样品的发光急剧下降,且随着C离子注入剂量的增加,发光峰出现明显红移。热退火处理的样品发光略有恢复。对发光峰进行拟合和分析结果表明,制备态的ZnO薄膜发光不仅出现本征发光,还在400 nm附近出现发光,在Fe和C双注入情况下,400 nm附近的发光仍然存在,这个发光主要来源于O空位。在450 nm附近也有个很宽的发光峰,这个发光峰主要来自于Zn的间隙子。除了ZnO本征发光外,其它的发光峰均来自于缺陷发光,注入导致样品中缺陷增多在一定程度上可以使发光增强,但是当缺陷浓度超过最佳掺杂浓度时,会引起发光淬灭。（5） PPMS磁性测试结果表明FeC3双注入的磁性要比Fe注入ZnO薄膜的磁性强,而Fe和FeC3退火样品的磁性比注入态样品的磁性有所下降。基于结构和表面成分的分析的结果对注入引起的ZnO薄膜的物性变化进行了讨论。更多还原

【Abstract】 ZnO thin films of thickness about 300 nm were deposited on microscopic glass substrates at room temperature by means of radio frequency （rf） magnetron sputtering. The ZnO thin films were first implanted with 120 keV Fe ions at a dose of 5.0?1016 cm^-2, and then subjected to 20 keV C ion implantation at different doses of 1.0?10¹⁵, 3?10¹⁵ and 5.0?10¹⁵ cm^-2, respectively. After implantation, some of the samples were annealed at 350℃in a flow of oxygen gas for 2 hrs. Techniques, such as scanning electron microscopy （SEM）, x-ray diffraction spectroscopy （XRD）, x-ray photoelectron spectroscopy （XPS）, ultraviolet-visible optical spectroscopy （UV-Vis）, photoluminescence （PL） and physics property measurement system （PPMS）, have been used to characterize the morphology, structure, composition, optical and magnetic properties of Fe and C co-implanted and/or annealed ZnO thin films. Through the research, the following results have been obtained.（i） SEM observations and EDX measurements reveal that Fe and/or C ion implantation leads to rough surface of ZnO films. The subsequent annealing could cause growth of ZnO grains. Meanwhile, the contents of main elements involved in ZnO films were found to decrease during Fe and/or C ion implantation and subsequent annealing. （ii） XRD results show that there exist two diffraction peaks in the as-deposited ZnO film, i.e. ZnO （002） and （004） peaks, which are located at 2?=34.6o and 72o, respectively. Fe ion implantation induces a new weak diffraction peak at about 44.4o, which corresponds to theα-Fe（110）, indicating formation of Fe nanoparticles. Additional C ion implantation not only gives rise to intensity decrease of theα-Fe（110） peak, but also the clear transformation of Fe nanoparticles into Fe oxide nanoparticles, which is confirmed by the occurrence of new diffraction peak at about 63°. Moreover, the structures of ZnO film under Fe and C co-implantation have also been studied in detail by consideration of modifications in ZnO （002） peak. The results show that lattice damage was created in Fe and C ion co-implanted ZnO films accompanied by clear growth of ZnO grains. The ZnO （002） peak was also found to shift to larger diffraction angle as the C ion dose increases. （iii） XPS measurements indicate that the chemical states of the implanted Fe atoms are mainly zero-valence state and compound-valence state, respectively. Carbon substitutes for oxygen and bonds with Zn, leading to formation of Zn-C bonds in the co-implanted ZnO films. （iv） UV-Vis measurements reveal that there only exists a strong absorption peak at wavelength of 380 nm in the as-deposited ZnO film. Fe ion implantation gives rise to decrease in the optical band gap of the ZnO film. However, it has been found that the optical band gap becomes larger in the Fe and C ion co-implanted ZnO samples. PL measurements demonstrate that in the Fe ion singly implanted ZnO, the PL property has been largely improved. Nevertheless, additional C ion implantation leads to sharp decrease of the luminescence. Moreover, with increasing C content, the slight red shift of PL peak has also been observed. The luminescence of the virgin ZnO could be divided into three peaks, which are located at 360, 400 and 450 nm, respectively. The PL peak at 360 nm could be attributed to the intrinsic luminescence of ZnO. The other two peaks should be mainly related to O vacancies and to Zn interstitials, respectively. Generally, the intensities of PL peaks related to defects increase with increasing the defect concentration. However, the luminescence disappeared if the concentration of defects was far over optimal concentration. （v） The results from PPMS measurements show that only a weak magnetism has been found in the Fe only implanted ZnO. The additional C implantation could increase the magnetism of the film. The subsequent annealing has been found to reduce the magnetism in both Fe singly implanted and Fe and C co-implanted ZnO film. Based on the results from the analyses of structures, the modifications in physical properties of ZnO under Fe and/or C ion implantation have been discussed.更多还原