中国物理B ›› 2008, Vol. 17 ›› Issue (10): 3753-3758.doi: 10.1088/1674-1056/17/10/037

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Trap states in oxidation layer of nanocrystal Si

秦朝建1, 黄伟其2, 王海旭2, 金 峰2   

  1. (1)Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003, China; (2)Key Laboratory of Photoelectron Technology and Application, Guizhou University, Guiyang 550026, China
  • 收稿日期:2008-02-23 修回日期:2008-04-09 出版日期:2008-10-20 发布日期:2008-10-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10764002).

Trap states in oxidation layer of nanocrystal Si

Huang Wei-Qi(黄伟其)a)†, Wang Hai-Xu(王海旭)a), Jin Feng(金峰)a), and Qin Cao-Jian(秦朝建)b)‡   

  1. a Key Laboratory of Photoelectron Technology and Application, Guizhou University, Guiyang 550026, China; b Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550003, China
  • Received:2008-02-23 Revised:2008-04-09 Online:2008-10-20 Published:2008-10-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10764002).

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摘要： The photoluminescence (PL) of nanocrystal present in porous silicon shifts from the near infrared to the ultraviolet depending on the size when the surface is passivated with Si-H bonds. After oxidation, the centre wavelength of PL band is pinned in a region of 700--750\,nm and its intensity increases obviously. Calculation shows that trap electronic states appear in the band gap of a smaller nanocrystal when Si = O bonds or Si--O--Si bonds are formed. The changes in PL intensity and wavelength can be explained by both quantum confinement and trap states in an oxidation layer of nanocrystal. In the theoretical model, the most important factor in the enhancement and the pinning effects of PL emission is the relative position between the level of the trap states and the level of the photoexcitation in the silicon nanocrystal.

关键词: photoluminescence, porous silicon, trap states

Abstract: The photoluminescence (PL) of nanocrystal present in porous silicon shifts from the near infrared to the ultraviolet depending on the size when the surface is passivated with Si-H bonds. After oxidation, the centre wavelength of PL band is pinned in a region of 700--750 nm and its intensity increases obviously. Calculation shows that trap electronic states appear in the band gap of a smaller nanocrystal when Si = O bonds or Si--O--Si bonds are formed. The changes in PL intensity and wavelength can be explained by both quantum confinement and trap states in an oxidation layer of nanocrystal. In the theoretical model, the most important factor in the enhancement and the pinning effects of PL emission is the relative position between the level of the trap states and the level of the photoexcitation in the silicon nanocrystal.

Key words: photoluminescence, porous silicon, trap states

中图分类号:  (Elemental semiconductors)

  • 78.55.Ap
78.67.Bf (Nanocrystals, nanoparticles, and nanoclusters) 78.55.Mb (Porous materials) 81.65.Mq (Oxidation) 73.22.-f (Electronic structure of nanoscale materials and related systems)