Hydrogen bubbles and formation of nanoporous silicon during electrochemical etching

Laxmikant Saraf, Donald R. Baer, Zheming Wang, James Young, Mark H. Engelhard, S. Thevuthasan

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Many nanoporous Si structures, including those formed by common electrochemical etching procedures, produce a uniformly etched nanoporous surface. If the electrochemical etch rate is slowed down, details of the etch process can be explored and process parameters may be varied to test hypotheses and obtain controlled nanoporous and defect structures. For example, after electrochemical etching of heavily n-doped (R = 0.05-0.5 Ω-cm) silicon (100) single crystals at a current density of 10 mA cm-2 in buffer oxide etch (BOE) electrolyte solution, defect craters containing textured nanopores were observed to occur in ringshaped patterns. The defect craters apparently originate at the hydrogen/BOE bubble interface, which forms during hydrogen evolution in the reaction. The slower hydrogen evolution due to low current density and high BOE viscosity allows sufficient bubble residence time so that a high defect density appears at the bubble edges where local reaction rates are highest. Current-carrying Si-OH species are most likely responsible for the widening of the craters. Reducing the defect/doping density in silicon lowers the defect concentration and thereby the density of nanopores. Measurements of photoluminescence lifetime and intensity show a distinct feature when the few nanopores formed at the ring edges are isolated from each other. Overall features observed in the photoluminescence intensity by XPS strongly emphasize the role of surface oxide that influences these properties.

Original languageEnglish
Pages (from-to)555-561
Number of pages7
JournalSurface and Interface Analysis
Volume37
Issue number6
DOIs
Publication statusPublished - Jun 2005
Externally publishedYes

Fingerprint

Electrochemical etching
Silicon
Oxides
Nanopores
Hydrogen
bubbles
etching
Defects
Buffers
defects
silicon
hydrogen
craters
Photoluminescence
Current density
oxides
buffers
Defect structures
Defect density
current density

Keywords

  • H/BOE/Si triple interface
  • Hydrogen bubbles
  • Nanoporous Si

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

Cite this

Saraf, L., Baer, D. R., Wang, Z., Young, J., Engelhard, M. H., & Thevuthasan, S. (2005). Hydrogen bubbles and formation of nanoporous silicon during electrochemical etching. Surface and Interface Analysis, 37(6), 555-561. https://doi.org/10.1002/sia.2048

Hydrogen bubbles and formation of nanoporous silicon during electrochemical etching. / Saraf, Laxmikant; Baer, Donald R.; Wang, Zheming; Young, James; Engelhard, Mark H.; Thevuthasan, S.

In: Surface and Interface Analysis, Vol. 37, No. 6, 06.2005, p. 555-561.

Research output: Contribution to journalArticle

Saraf, L, Baer, DR, Wang, Z, Young, J, Engelhard, MH & Thevuthasan, S 2005, 'Hydrogen bubbles and formation of nanoporous silicon during electrochemical etching', Surface and Interface Analysis, vol. 37, no. 6, pp. 555-561. https://doi.org/10.1002/sia.2048
Saraf, Laxmikant ; Baer, Donald R. ; Wang, Zheming ; Young, James ; Engelhard, Mark H. ; Thevuthasan, S. / Hydrogen bubbles and formation of nanoporous silicon during electrochemical etching. In: Surface and Interface Analysis. 2005 ; Vol. 37, No. 6. pp. 555-561.
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