Semiconductor surface and interface passivation by cyanide treatment

H. Kobayashi, M. Takahashi, O. Maida, A. Asano, T. Kubota, J. Ivančo, A. Nakajima, K. Akimoto

研究成果: Conference article査読

14 被引用数 (Scopus)

抄録

Cyanide treatment which simply involves immersion of semiconductors in cyanide solutions can passivate interface states as well as surface states. When Si surfaces are treated with KCN solutions, a surface photovoltage greatly increases, and the surface recombination velocity is calculated to be decreased from ∼3000 cm/s to less than 200 cm/s. When the cyanide treatment is applied to ultrathin SiO 2 /single-crystalline Si structure, interface states are passivated. The passivation of the SiO 2 /Si interface states increases the energy conversion efficiency of 〈indium tin oxide (ITO)/SiO 2 /Si〉 MOS solar cells to 16.2% and decreases the leakage current density for 〈aluminum (Al)/SiO 2 /Si〉 MOS diodes to 1/3-1/8. When the cyanide treatment is performed on polycrystalline (poly-) Si, defect states in Si up to at least 0.5 μm depth from the surface are passivated, resulting in a vast increase in the energy conversion efficiency of 〈ITO/SiO 2 /poly-Si〉 solar cells and a decrease in the dark current density of 〈Al/SiO 2 /poly-Si〉 MOS diodes to 1/100-1/15 that without cyanide treatment. The defect passivation is attributed to the formation of Si-CN bonds from defect states. Si-CN bonds are found not to be ruptured by heat treatment at 800°C and AM 1.5 100 mW/cm 2 irradiation for more than 1000 h. Density functional calculations show that the thermal and irradiation stability results from strong Si-CN bonds with the bond energy of 4.5 eV. When the cyanide treatment is performed on oxide/GaAs(1 0 0) structure, the interface state density decreases to ∼50%. The cyanide treatment can also passivate defect states in Cu 2 O films, resulting in increases in the carrier density and the band-to-band photoluminescence intensity.

本文言語English
ページ(範囲)279-292
ページ数14
ジャーナルApplied Surface Science
235
3
DOI
出版ステータスPublished - 2004 8月 15
イベントProceedings of 3rd International Workshop on Semiconductor - Ustron, Poland
継続期間: 2003 9月 152003 9月 17

ASJC Scopus subject areas

  • 化学 (全般)
  • 凝縮系物理学
  • 物理学および天文学(全般)
  • 表面および界面
  • 表面、皮膜および薄膜

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