Compaction of nanosilicon pellets and sol-deposited films via high-vacuum annealing

1. Download : Download high-res image (121KB)
2. Download : Download full-size image

     

内电场对纳米硅光致发光谱的影响

从量子限制发光中心模型出发，计算了纳米硅的光致发光（PL）特征与发光中心间的关系. 研究发现，纳米硅与发光中心间的内电场对载流子复合率及峰位振荡有着十分重要的影响. 在2—5 nm的尺寸范围内，纳米硅发光中心上的载流子复合概率远大于内部复合概率，仅需考虑发光中心上的载流子复合发光. 还发现发光中心与纳米硅粒子间的内电场对于纳米硅的发光峰位振荡有着显著的影响.发光中心与纳米硅粒子间的内电场的存在会显著减小纳米硅粒子的内部发光效率以及外部相应发光中心上的发光强度，使得纳米硅PL谱的峰位随纳米晶粒尺寸变化而发生 关键词： 内电场 纳米硅 光致发光 量子限制发光中心     

热退火、激光束和电子束等作用对纳米硅制备及其局域态发光特性的影响

在纳米晶体硅制备的过程中, 晶化处理是影响和提高纳米硅发光效率的重要制备环节. 热退火、激光退火和电子束辐照是使纳米硅样品晶化的不同方式. 实验表明: 选取适当的晶化方式和参量对制备纳米硅晶体结构至关重要, 特别是在制备硅量子点和量子面的过程中控制好参量, 可以得到较高的发光效率. 有趣的是, 在实验中发现: 当晶化时间较短(如低于20 min)时, 可以获得较好的纳晶硅结构(如量子点结构), 对应于较好的纳晶硅光致发光(PL)和掺杂局域态发光; 当晶化时间较长(如超过30 min)时, 纳米晶体硅结构被破坏, 致使PL谱逐渐减弱与消失. 结合热退火、激光退火和电子束辐照对纳米硅晶化过程, 本文建立起晶化时间对纳米硅局域态发光影响机理的物理模型, 解释了晶化时间对纳米硅局域态发光的影响.     

Nanosilicon stabilized with ligands: Effect of high-energy electron beam on luminescent properties

Silicon nanopowders with nitrogen heterocyclic carbene (NHC) and butyl as stabilizing ligands were synthesized by bottom up chemical methods. Transmission electron microscopy (TEM) was used to obtain nanoparticle size distribution with 1.8–2.5 mm average diameter. Optical characteristics (photoluminescence and infrared (IR) absorption spectra) of samples were investigated as fabricated and on different steps of irradiation by high-energy 7-MeV electrons. The photoluminescence (PL) spectral changes are slightly different for two cases, but in general, we can see a decrease in luminescence amplitude with fluence growth up to 1.2·10¹⁶ cm⁻², mainly for NHC stabilized nanosilicon. Main mechanisms of radiation-induced changes in nanosilicon sample optical properties are discussed by the joint use of PL and IR spectra analysis.