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Fabrication and surface modification of micro/nanoporous silicon

J. P. KAR1,* , S. K. MOHANTA2, G. BOSE1, S. TULI1, A. KAMRA3, V. MATHUR4

Affiliation

  1. Centre for Applied Research in Electronics, IIT Delhi, India, 110016
  2. Department of Physics, IIT Delhi, India, 110016
  3. Kurukshetra University, Kurukshetra, India
  4. Manipal Institute of Technology, Banglore, India

Abstract

We have studied surface and structural properties of micro/nanoporous silicon, synthesized by electrochemical etching of ptype Si (100) with different etching conditions. SEM studies reveal tunable pore sizes from 200 nm to 1.5 μm for etching time 5 to 30 min, and the thickness of pore walls decreases upto 20 nm for 30 min etching. AFM investigations reveal increase in roughness of the porous structure with increase in etching time and saturate around 250 nm at higher etching time. X-ray diffractogram of porous Si surface for etching time 20 min shows the appearance of two peaks at 2θ = 69.13º and 69.33º. For 30 min etching time a broad peak is observed at 2θ = 69.39º. The broadening may due to the size distributions of pore walls, and up ward shifts may due to relaxation of strain in the porous structure. FTIR investigations show the presence of Si-H bending in Si3-SiH groups at 624 cm-1, Si-O stretching in O-Si-O in between 1056-1160 cm-1. The bands at 2958, 2927, and 2856 cm-l are related to C-H stretching of CH3, CH2, and CH groups, which probably come from residual of HF-dimethylformamide..

Keywords

Porous Si, SEM, XRD, FTIR.

Submitted at: April 2, 2008
Accepted at: March 24, 2009

Citation

J. P. KAR, S. K. MOHANTA, G. BOSE, S. TULI, A. KAMRA, V. MATHUR, Fabrication and surface modification of micro/nanoporous silicon, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 3, pp. 238-242 (2009)