Photonic crystals in biology - NanoTR-VI

Poster Session, Thursday, June 17Theme F686 - N1123CRYSTALLIZATION OF THIN Si FILM FABRICATED BY ELECTRON BEAMEVAPORATION ON GLASS SUBSTRATE FOR SOLAR CELLL APPLICATIONSM. Karaman a , Ö. Tüzün b , R. Turan a , . Oktik ba Department of Physics, Middle East Technical University, 06531 Ankara, Turkeyb Department of Physics, Mula University, 48000 Mula, TurkeyE-Mail: mkaramanm@gmail.comAbstractAmorphous, nanocrystalline andpolycrystalline silicon thin films fabricatedon glass substrate are of great interest forlow-cost and high efficiency solar cells.There are various techniques to fabricatesuch kind of cells[1]. Solid PhaseCrystallization (SPC) technique isfavourable due to its easy production andresulting high quality, such as largergrained, less defective thin films. However,its long crystallization annealing is thedisadvatage for industrial productionapplication[2]. This important problem issolved by a novel annealing technique thatconsists of two-step annealing. These arelow-temperature annealing (475 o C for 8h) tostart the nucleation with a lower nucleationrate and high-temperature annealing (900 o Cfor 1h) to reduce the annealing timedramatically. In this approach, novel SPCprocess results larger grain size with lowerdefects compared to conventional lowtemperatureSPC process while the hightemperatureannealing reduces thecrystallization time. This two step annealingprocesses lead to a phase transformationfrom a fully amorphous phase to ananocrystalline phase and finally apolycrystalline phase in the film. This workaims to undertand the basic kintics in thesetransformation processes.Ex situ doped amorphous silicon isdeposited by electron beam evaporationsystem with a depositon rate of 3Å/sec, andcrystallized by classical thermal process.The structural analysis of the films formedby this novel annealing process is analyzedby optical microscopy, scanning electronmicroscopy (SEM), electron back scatteringdiffraction (EBSD) technique, and RamanSpectroscopy. Raman spectroscopy allowedus to monitor the crystallinity of the grownlayer. It also provided infromation about theFigure1. Raman measurement after 475°C 8h+900°C60min annealing processstructures formed at nanoscale. Dopingprofile of boron through the active layer isstudied by secondary ion mass spectroscopy(SIMS). Results show that structures withnanometer dimension are observable evenafter high temeparture annealings.[1] T. Baba, M. Shima, T. Matsuyama, S. Tsuge, K.Wakisaka, S. Tsuda, In: Proc. 13 th European PhotovoltaicSolar Energy Conf. (1995) 1708.[2] T. Baba, T. Matsuyama, T. Sawada, T. Takahama, K.Wakisaka, S. Tsuda, MRS Symp. Proc. 358 (1995) 8956th Nanoscience and Nanotechnology Conference, zmir, 2010 768