Films minces à base de Si nanostructuré pour des cellules ...

Reactive method: Si cathode is sputtered while introducing nitrogen into the
Ar plasma to obtain Si-rich silicon nitride (SRSN). A sample of N-rich silicon nitride
(NRSN) was obtained by sputtering a Si 3 N 4 target in N-rich plasma.
Co-sputtering method: this approach involves the simultaneous co-sputtering
of Si 3 N 4 and Si cathodes. The power density on Si 3 N 4 was xed at 7.4 W/cm 2 and
that on Si cathode was varied between 0-2.96 W/cm 2 in order to see the eect of
excess Si incorporation.
Silicon dioxide (SiO 2 )
Silicon dioxide layer was deposited by sputtering SiO 2 cathode under pure Ar plasma.
As in the previous cases, the RF power density on the SiO 2 cathode was maintained
at 7.4 W/cm 2 .
tel-00916300, version 1 - 10 Dec 2013
The single layers and the multilayers of SiO 2 , SRSO and SiN x were synthesized
using the growth methods described above. The composition of the layers were
varied using appropriate deposition conditions such as temperature, pressure, RF
power density monitored using a computer software provided by AJA International.
To deposit at a desired temperature a ramp time was fed in the program to reach
the temperature and a dwell time of 1 hour was xed for stabilization (to reach
a uniform temperature over the substrate) before the deposition takes place. The
substrate was kept under rotation with a speed of 20 revolutions/minute to ensure
homogeneous deposition and the substrate-target distance was xed at 38 cm.
2.1.3 Thermal treatment
All the deposited layers were subjected to thermal treatments in order to favour
phase-separation, crystallization and passivation of the defects (vacancy, dangling
bonds, etc.) in the material. All the samples were annealed under the nitrogen atmosphere
and the temperatures of annealing was varied between 400-1100 °C depending
on the requirement. A couple of multilayers were also subjected to annealing under
the forming gas atmosphere between 380°C-500°C. The eect of the annealing time
and temperatures of dierent kinds of layers were analyzed.
2.2 Structural and Optical Characterization
The samples in this thesis have been analyzed structurally and optically using one
or many of the following techniques: Fourier Transform Infrared Spectroscopy, X-
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