Si implantation in SiO₂: Stucture of Si nanocrystals and composition of SiO₂ layer

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• 作者：V. Levitcharsky ; R.G. Saint-Jacques ; Y.Q. Wang ; L. Nikolova ; R. Smirani ; G.G. Ross
• 关键词：Si implantation ; Si nanocrystals ; SiO₂ ; HRTEM ; Photoluminescence ; XPS
• 刊名：Surface and Coatings Technology
• 出版年：2007
• 期刊代码：106_02578972
• 类别：ms
• 出版时间：5 August 2007
• 卷：201
• 期：19-20
• 页码：8547-8551
• 文件大小：743 K

摘要

Silicon is known to be a poor light emitter. However, once in nanometer scale, it can emit a strong visible and infrared light after excitation. Si nanocrystals (Si-nc) with a diameter of <img src="http://www.sciencedirect.com/scidirimg/entities/223c.gif" alt="not, vert, similar" border=0> 3 nm are produced by implantation of Si ions into amorphous SiO₂ followed by thermal annealing. These Si-nc could allow the use of Si for making luminescent devices compatible with optoelectronic integrated circuits. Si ions have been implanted with an energy of 50 and 100 keV to fluences ranging from 2 × 10¹⁶ to 3 × 10¹⁷ Si/cm². The effect of Si implantation fluence on the microstructure of the Si-nc and the SiO₂ matrix has been examined using TEM and XPS. The size, spatial distribution and concentration of the Si-nc have been investigated by TEM and compared to the depth distribution of implanted Si ions. A crystalline structure of the Si-nc has been observed for local Si concentration in excess larger than <img src="http://www.sciencedirect.com/scidirimg/entities/223c.gif" alt="not, vert, similar" border=0> 3 × 10²¹ Si/cm³. Moreover, defects (twins, SF's) and faceting have been observed by HRTEM in Si-nc larger than 6 nm. These large Si-nc are produced with a local Si concentration in excess larger than <img src="http://www.sciencedirect.com/scidirimg/entities/223c.gif" alt="not, vert, similar" border=0> 1 x 10²² Si/cm³. XPS has revealed the presence of an oxygen poor surface layer in the SiO₂. This effect of oxygen depletion is also visible in TEM over a layer of <img src="http://www.sciencedirect.com/scidirimg/entities/223c.gif" alt="not, vert, similar" border=0> 25 nm.