Nanostructured Porous Si And Gan Fabricated By Electrochemical And Laser Induced Etching Techniques
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Date
2011-08
Authors
Abd-Alghafour, Asmiet Ramizy
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Porous Si (PS) and Porous GaN (PGaN) nanostructures have been produced
by electrochemical and laser-induced etching techniques, respectively. Radiofrequency
(RF) nitrogen plasma-assisted molecular beam epitaxy (PA-MBE)
technique was used to grow the GaN sample while a commercial silicon wafer was
used. The etching mechanism and the parameters that produce the different
nanostructures are discussed. The control of the size and the shape of present
nanostructures were investigated by modifying several etching parameters: current
density, laser power density, etching time, and electrolyte solution. The surface
morphologies of PS and PGaN verify that pore diameter and nanostructure are
dependent on the etching parameters, and that the shifting towards shorter
wavelength is due to the diminishing quantum confinement dimension of the sample
skeletons where blue shift of wavelength increases along with porosity. Two
methods have been used for porosity measurement namely, conventional method
(weighing method) and image processing (IP) method. A more accurate method
based on IP function analysis was developed to determine the porosity percentage of
the samples. According to the quantum confinement luminescence model, the shorter
peak wavelength of luminescence has caused the increase in the energy band gap
(Eg) of the porous structure. A novel technique using integrated electrochemical and
laser-induced etching to produce Si nanowires with high consistency in its final
shape and resultant nanostructures is presented here. Solar cells based on
electrochemically etched PS surfaces were fabricated, and the effect of the porosity
of the silicon surface on the cell efficiency was investigated.
Description
Keywords
Nanostructured Porous , Laser Induced Etching Techniques