Si/C多层薄膜中硅纳米晶的微结构演化

Microstructure Evolution of Si Nanocrystals in Si/C Multilayer Films

摘要:

通过磁控溅射技术和1100 ℃的高温后续退火处理,在Si/C多层薄膜中形成硅纳米晶。改变多层薄膜的调制波长比可以调控硅纳米晶的尺寸、形状和密度。其微观结构由小角X射线、拉曼频移、高分辨电镜进行表征。结合拉曼频移和高分辨电镜分析表明,由于受到C层界面约束,非晶硅层在高温下会发生固态重结晶,转变为纳米晶。通过调制波长比可调控纳米晶的尺寸和形状。当调制波长比从0.5到2改变时,硅纳米晶的形状逐渐从球形、椭圆形转变为条形或者砖型。夹层受限生长模式有利于适应新一代硅基光电子器件的结构设计。

Abstract:

Si/C multilayer films deposited by radio frequency magnetron sputtering were post-annealed at 1100°C for 1 h to produce Si nanocrystals (NCs). X-ray diffraction and Raman spectroscopy were used to analyze the phase composition and atomic vibration spectrum of the multilayer structure. High-resolution transmission electron microscopy was employed to verify the existence of Si NCs and to observe their sizes and morphologies. The results reveal that the Si NCs were formed by solid-phase recrystallization of the nanometer-thick layers of amorphous Si confined between C layers. The NC shape and size could be tuned by changing the modulation ratio of the Si layer and the C layer. When the ratio shifted from 0.5 to 2, the NCs became spherical, elliptical, square, and brick-shaped. This growth mode may be conducive to the design of different Si-based photo-electronic materials...