【作者】 鲁颖炜；

【导师】 孙景； 杜希文；

【作者基本信息】 天津大学 ， 材料学， 2008， 博士

【摘要】 自从英国科学家L.T.Canham成功制备出具有可见光发射性能的多孔硅(PS)后,以电子领域最重要的半导体硅(Si)作为发光材料的研究引起了广泛关注。而Si纳米晶作为零维纳米材料以其特有的量子限制效应成为所有Si纳米结构发光研究中的热点。本论文通过改变Si的晶体结构实现了Si纳米晶材料的高效发光,通过硅-银(Si-Ag)键表面钝化PS实现Si纳米晶材料的高强度稳定发光,并欲通过实现Si纳米晶有序分布实现Si纳米晶材料发光均匀化。研究发现,采用低成本、无污染的偏压溅射法可以制备出具有蓝光和紫外光发射的面心立方结构Si(fcc-Si)纳米晶材料。同时通过对比金刚石结构Si(dc-Si)纳米晶材料的发光性能和吸收性能发现,虽然fcc-Si纳米晶仍然属于间接带隙半导体,但fcc-Si纳米晶/Si氧化物系统的发光效率更高,约为dc-Si纳米晶/Si氧化物系统的1.2～1.6倍。另外,通过低成本、工艺简单的电化学阳极氧化和电化学沉积二步法制备出具有Si-Ag键表面钝化的PS。研究结果表明,具有最佳钝化效果的PS的发光强度是普通PS的3倍,且具有更高的发光稳定性。钝化后PS的发光强度与表面Si-Ag键的数量紧密相关:首先随着表面键数量的增多而强度增大,表面键饱和后强度达到最大,随后随着沉积Ag数量的增多,PS的发光发生淬灭。本论文同时通过理论和试验对Si纳米晶的有序分布做了初步探讨。首次用Monte Carlo方法模拟了应变场作用下Si原子在非晶氧化硅隔离层上的分布状态。结果表明,应变场确实对Si原子最终分布的区域具有调控作用,从理论上证明在非晶基体中, Si纳米晶同样可以实现应变场驱动的有序分布。试验方面,通过偏压共溅射加后续退火的方法成功制备了目前最高面密度的Si纳米晶(约7×1012 cm-2,比当前文献报道的Si/氧化硅系统的最高密度高5～10倍)。高分辨电镜照片显示Si纳米晶呈现部分有序化,发光谱显示只存在一个发光峰,初步显现了发光均匀性特征。更多还原

【Abstract】 Si, as the most semiconductor materials in the field of electronic industry, has attracted wide interest since porous silicon (PS) with visible-light emission has been fabricated by L.T.Canham who is an English scientist. And luminescent Si nanocrystals (nc-Si), as 0-dimensional materials, have become one of the hottest issues in the research on Si nanostructres due to their unique quanum confinement effect.In this thesis, we improved photoluminescence (PL) efficiency through changing the crystalline structure of nc-Si, enhanced PL intensity and stability through passivation of Si-Ag bonds in surface of PS, and realized PL simplification, which means PL spectrum with single and narrow peak, through ordering of nc-Si.The research results indicate that fcc nc-Si with blue- and violet-light emission can be prepared by magnetron sputtering with substrate bias, one kind of low-cost and free-pollution method. After comparing characterization between fcc nc-Si and dc nc-Si, we can conclude that although fcc nc-Si contain the intrinsic character of indirect band gap, PL efficiency of fcc nc-Si/SiO2 system is higher than that of dc nc-Si/SiO2 system and the former is latter’s 1.2 to 1.6 times.PS with Si-Ag bonds passivation can be prepared by using low-cost, simple two-step technique, combining electrochemical anodization and electrochemical deposition. The research results reveal that PL intensity of passivated PS is 3 times of that of normal PS and PL stability of passivated PS is much better than that of normal PS. PL intensity of passivated PS depend on the number of Si-Ag bonds: at first, PL intensity increase with number of Si-Ag bonds, then PL intensity reach the maximum when Si-Ag bonds are saturated, at last, PL vanish due to superfluous Si-Ag bonds.In addition, we discussed ordering of nc-Si in both theoretical and experimental aspects. In theoretical aspect, we firstly simulated distribution of Si atoms on the amorphous SiO2 buffer layer under the effect of strain field by using Monte Carlo method. The results indicate that Si atoms tend to congregate in some particular zones due to existence of strain field. Therefore, we proved that ordering of nc-Si can be realized under strain field. In experimental aspect, we prepared nc-Si with highest area density (about be 7×1012 cm-2, and is 5 to 10 times of highest density which be reported up to now) by using magnetron sputtering with substrate bias combined with post-annealing. High resolution transmission electron microscope (HRTEM) images and PL spectra with only one PL peak respectively show that partial ordering and PL simplication of nc-Si have been realized.更多还原