Third Day Poster Session, 17 June 2010 - NanoTR-VI

Poster Session, Thursday, June 17
Theme F686 - N1123
CRYSTALLIZATION OF THIN Si FILM FABRICATED BY ELECTRON BEAM
EVAPORATION ON GLASS SUBSTRATE FOR SOLAR CELLL APPLICATIONS
M. Karaman a , Ö. Tüzün b , R. Turan a , . Oktik b
a Department of Physics, Middle East Technical University, 06531 Ankara, Turkey
b Department of Physics, Mula University, 48000 Mula, Turkey
E-Mail: mkaramanm@gmail.com
Abstract
Amorphous, nanocrystalline and
polycrystalline silicon thin films fabricated
on glass substrate are of great interest for
low-cost and high efficiency solar cells.
There are various techniques to fabricate
such kind of cells[1]. Solid Phase
Crystallization (SPC) technique is
favourable due to its easy production and
resulting high quality, such as larger
grained, less defective thin films. However,
its long crystallization annealing is the
disadvatage for industrial production
application[2]. This important problem is
solved by a novel annealing technique that
consists of two-step annealing. These are
low-temperature annealing (475 o C for 8h) to
start the nucleation with a lower nucleation
rate and high-temperature annealing (900 o C
for 1h) to reduce the annealing time
dramatically. In this approach, novel SPC
process results larger grain size with lower
defects compared to conventional lowtemperature
SPC process while the hightemperature
annealing reduces the
crystallization time. This two step annealing
processes lead to a phase transformation
from a fully amorphous phase to a
nanocrystalline phase and finally a
polycrystalline phase in the film. This work
aims to undertand the basic kintics in these
transformation processes.
Ex situ doped amorphous silicon is
deposited by electron beam evaporation
system with a depositon rate of 3Å/sec, and
crystallized by classical thermal process.
The structural analysis of the films formed
by this novel annealing process is analyzed
by optical microscopy, scanning electron
microscopy (SEM), electron back scattering
diffraction (EBSD) technique, and Raman
Spectroscopy. Raman spectroscopy allowed
us to monitor the crystallinity of the grown
layer. It also provided infromation about the
Figure1. Raman measurement after 475°C 8h+900°C
60min annealing process
structures formed at nanoscale. Doping
profile of boron through the active layer is
studied by secondary ion mass spectroscopy
(SIMS). Results show that structures with
nanometer dimension are observable even
after high temeparture annealings.
[1] T. Baba, M. Shima, T. Matsuyama, S. Tsuge, K.
Wakisaka, S. Tsuda, In: Proc. 13 th European Photovoltaic
Solar Energy Conf. (1995) 1708.
[2] T. Baba, T. Matsuyama, T. Sawada, T. Takahama, K.
Wakisaka, S. Tsuda, MRS Symp. Proc. 358 (1995) 895
6th Nanoscience and Nanotechnology Conference, zmir, 2010 768