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Semiconductor surface and interface passivation by cyanide treatment
- Source :
-
Applied Surface Science . Aug2004, Vol. 235 Issue 3, p279-292. 14p. - Publication Year :
- 2004
-
Abstract
- 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 SiO2/single-crystalline Si structure, interface states are passivated. The passivation of the SiO2/Si interface states increases the energy conversion efficiency of 〈indium tin oxide (ITO)/SiO2/Si〉 MOS solar cells to 16.2% and decreases the leakage current density for 〈aluminum (Al)/SiO2/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/SiO2/poly-Si〉 solar cells and a decrease in the dark current density of 〈Al/SiO2/poly-Si〉 MOS diodes to 1/100–1/15 that without cyanide treatment. The defect passivation is attributed to the formation of Si&z.sbnd;CN bonds from defect states. Si&z.sbnd;CN bonds are found not to be ruptured by heat treatment at 800 °C and AM 1.5 100 mW/cm2 irradiation for more than 1000 h. Density functional calculations show that the thermal and irradiation stability results from strong Si&z.sbnd;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 Cu2O films, resulting in increases in the carrier density and the band-to-band photoluminescence intensity. [Copyright &y& Elsevier]
- Subjects :
- *IRRADIATION
*DIRECT energy conversion
*PHOTOVOLTAIC cells
*SOLAR energy
Subjects
Details
- Language :
- English
- ISSN :
- 01694332
- Volume :
- 235
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Applied Surface Science
- Publication Type :
- Academic Journal
- Accession number :
- 14188004
- Full Text :
- https://doi.org/10.1016/j.apsusc.2004.05.101