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纳米硅和多孔硅发光的发现,引起了人们对纳米级半导体材料研究的重视.对这种现象的解释主要归结为以下两点:一是因颗粒尺寸小而引起能带结构的变化,导致跃迁选择定则改变引起发光,即所谓量子尺寸效应;二是在硅小颗粒表面的氢、氧等杂质与硅化合形成缺陷,悬键所引起发光。目前对这两种解释尚无定论。对于后者,弄清楚纳米硅中氢、氧的存在方式与结构的关系对研究纳米硅的发光机理有很重要的意义。红外吸收光谱作为探测硅中的氢、氧等的手段已进行了很多的研究。本文利用激光诱导化学气相沉积法(LICVD)用SiH_4为原料制备了平均粒度为10～12nm的晶态纳米硅粉。并通过红外吸收光谱对纳米硅粉末中的氢和表面氧化所引起的氧的存在情况进行了分析。发现纳米硅粉末由于表面原子活性大,有氧化现象,在其中存在(H_2-Si)。原于团和HSiO两种类型的硅氢结构。前者是一种不稳定结构,退火温度达到600℃时分解,在红外谱上的吸收峰消失;后者是一种稳定结构,随退火温度的升高,氧含量的增多,向高波数方向移动。这主要是由于氧的电负性对H-Si的影响形成的。
The discovery of nanosized silicon and porous silicon luminescence has aroused people’s attention on the research of nanoscale semiconductor materials. The explanation of this phenomenon mainly comes down to the following two points: First, the change of the band structure due to the small size of the particles leads to the transition Select the rules to change the cause of light, the so-called quantum size effect; the second is small particles of silicon surface hydrogen, oxygen and other impurities and silicon formation defects, dangling bonds caused by the light. At present, there is no conclusion about these two explanations. For the latter, it is very important to understand the relationship between the existence and structure of hydrogen and oxygen in the nano-silicon to study the luminescence mechanism of nano-silicon. Infrared absorption spectroscopy as a means of detecting silicon in hydrogen, oxygen, etc., has been a lot of research. In this paper, the crystalline nanosilica with average particle size of 10 ~ 12nm was prepared by laser induced chemical vapor deposition (LICVD) using SiH_4 as raw material. The existence of oxygen due to hydrogen and surface oxidation of nano-silicon powder was analyzed by infrared absorption spectroscopy. It was found that due to the large surface atomic activity of nanosilica powder, there is an oxidation phenomenon in which (H 2 -Si) is present. The original group and HSiO two types of hydrosilicide structure. The former is an unstable structure, the annealing temperature reaches 600 ℃ decomposition, the absorption peak in the infrared spectrum disappears; the latter is a stable structure, with the annealing temperature increases, the oxygen content increased, to the high wave number direction . This is mainly due to the influence of the electronegativity of oxygen on the H-Si.