Formation of Silicon Nanocrystallites by Electron Cyclotron Resonance Chemical Vapor Deposition and Ion Beam Assisted El
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ABSTRACT Nano-crystalline silicon (nc-Si) thin films were directly deposited by electron cyclotron resonance chemical vapor deposition (ECR-CVD) and ion beam assisted electron beam deposition (IBAED) method. In the sample deposited by ECR-CVD, the room temperature photoluminescence originated from the nc-Si and the silicon-hydrogen bond were appeared. It was confirmed that the size of the nc-Si could be controlled up to about 3 nm with the low substrate temperature during the deposition process and then the hydrogen atoms play a very important role in the formation of the nc-Si. The IBAED method was also found to an useful technique for nc-Si formation by the control of ion beam power. INTRODUCTION With increasing the interest about the emission from the silicon semiconductors such as porous silicon and nano-sized silicon crystallites, the various methods [1-3] has been attempted for fabrication of the silicon-based light emitting devices. Especially, in the case of the nanocrystalline silicon (nc-Si), it was reported that the wavelength of the emission can be controlled
with respect to the size of nc-Si. Also, the application as an optoelectronic device may be feasible because of having the surface smoother than that of porous. There are many methods for the formation of nc-Si [4-6]. The formation of the nc-Si through the post-annealing was a widely known method. In recent, a direct formation of nc-Si has been attempted by many researchers [7,8]. Moreover, one of the greatest challenges has been the integration of nano-sized silicon crystallites materials into serviceable architectures such as electroluminescence devices. However, the efficiency of the emission from nc-Si is very low yet, because of the low density of nc-Si and the wide range of size distribution. In this work, we introduce the new methods, the electron cyclotron resonance chemical vapor deposition (ECR-CVD) and the ion beam assisted electron beam deposition (IBAED), for direct formation of the nc-Si. In the ECR-CVD method, the size of the crystallites could be controlled by the change of the substrate temperature during the deposition process. Also, it was confirmed that hydrogen atoms play a very important role on the formation of nc-Si using ECR-CVD. On the other hand, the IBAED method showed that the size and density of the nc-Si might be controlled by the various conditions of the ion beam. EXPERIMENT The amorphous silicon thin films were deposited at various temperatures by the ECR-CVD and the IBAED methods on silicon and silicon dioxide substrates, respectively. During the 231 Mat. Res. Soc. Symp. Proc. Vol. 486 01998 Materials Research Society
ECR-CVD process, high quality (99.999 %) silane (SiH 4) and argon (99.995 %) were used as the source and the carrier gases, respectively. The flow rates of the silane and the argon gases were 40 and 5 sccm, respectively, and the working pressure was 9-7x 1 0 4 Torr. The power of the ECR was 300 W and the substrate temperature was changed from 50 to 200 1C. The IBAED was performed at room temperatu
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