TITLE:
Infrared Transmission in Porous Silicon Multilayers
AUTHORS:
Alessio Palavicini, Chumin Wang
KEYWORDS:
Porous Silicon; Multilayer; Infrared Transmission; Quasiperiodicity
JOURNAL NAME:
Optics and Photonics Journal,
Vol.3 No.2A,
June
20,
2013
ABSTRACT: Porous silicon is a nanostructured material and exhibits
efficient photo- and electro-luminescence in the visible range at room
temperature, as well as a tunable refractive index determined by its porosity.
Porous silicon samples can be obtained by etching a crystalline silicon wafer
in a solution of hydrofluoric acid. In this work, we report the fabrication of
porous silicon multilayers alternating layers with high and low porosities,
which correspondingly produce low and high refractive indices. The
free-standing multilayers were formed following three different sequences:
periodic, Fibonacci and ThueMorse. These structures were verified by scanning
electron microscopy and their infrared transmission spectra
were measured by means of Fourier-transform infrared spectroscopy. On the other
hand, we calculate the light transmittance of porous silicon multilayers by
using the transfer matrix method for all directions of incidence and a wide
range of wavelengths. The experimental measurements are compared with
theoretical results and a good agreement is observed. In addition, an analysis of
infrared absorption peaks due to the molecular vibrations at pore surfaces
reveals the presence of hydrogen and oxygen atoms.