산화아연을 이용한 층교환 성장법을 통한 다결정 실리콘 박막의 성장에 관한 연구

Abstract

High-quality polycrystalline silicon (poly-Si) has attracted much attention because of its wide range of applicability in electronics, such as thin-film transistors (TFT) and solar cell. However, growth of poly-Si layer on a low cost substrate with large area is still difficult. In this thesis, it was proposed to grow poly-Si layer on a glass substrate by layer exchange method on ZnO layer, and the effect of ZnO surface and annealing temperature was discussed in terms of growth rate, crystallized fraction, diameter, and orientation of poly-Si nuclei.

First of all, it has been investigated on the effect of surface roughness of zinc oxide (ZnO) layer on the growth of poly-Si layer. It was found that the growth rate, grain size, crystallized fraction and preferential orientation are closely related with the surface roughness of the underlying ZnO layer. As the ZnO surface roughens, growth rate, grain size, and crystallized fraction increase, and preferential orientation of (100) direction was appeared as well. The poly-Si layer formed on a ZnO with a roughness of 2.4 nm in root-mean-square revealed fast growth rate (40 minutes), large grain size (~20 μm) and high crystallized fraction (51 %) with a preferential (100) orientation.

In the next part, it has been investigated on the effect of annealing temperature to the layer exchange process. Annealing was performant at 500 ~ 600oC. It was found that the preferential orientation and growth rate of poly-Si layer is closely related with the annealing temperature. As the annealing temperature increasing, faster growth rate, larger crystallized fraction and (100) preferential orientation was observed.

Consequently, it was provided that a new approach to obtain large grain size poly-Si on glass substrate that contains ZnO light scattering and transparent conducting layer. It is expected to be used for the high performance thin film poly-Si based solar cell.