|
Semiconductor Physics, Quantum Electronics & Optoelectronics. 2007. V. 10, N 1. P. 060-066.
Graded refraction index antireflection coatings
based on silicon and titanium oxides
Laboratoire des Matériaux et Structures des Systèmes Electromécaniques et leur Fiabilité (LMSSEF) Centre
universitaire L. Benmhidi BP 358, 04000 O.E.Bouaghi Algeria
e-mail: abdelmah@yahoo.com
Abstract. Thin films with a graded refraction index constituted from silicon and titanium
oxides were deposited by plasma enhanced chemical vapor deposition using electron
cyclotron resonance. A plasma of oxygen reacted with two precursors: the
tetraethoxysilane (TEOS) and the titanium isopropoxide (TIPT). The automatic
regulation of the precursor flows makes it possible to modify the chemical composition,
and consequently the optical index, through the deposited films. To control the thickness,
the refraction index and the growth kinetics, in situ spectroscopic ellipsometer was
adapted to the reactor. The analysis of ex situ ellipsometric spectra measured at the end
of each deposition allow to determine a refraction index profile and optical properties of
the inhomogeneous deposited films. Measurements of reflectivity carried out in the
ultraviolet-visible-near infrared range show that these films could be used as
antireflective coatings for silicon solar cells: 3.7 % weighted average reflectivity between
300 and 1100 nm and 48 % improvement of the photo-generated current were obtained.
Keywords: ellipsometry, graded index, AR coating.
| ||