박형 실리콘 형성을 위한 습식 공정 및 그의 활용에 관한 연구

Abstract

Single crystalline silicon(c-Si) is extensively used semiconducting material for VLSI, solar cells, MEMS and other applications. Among these applications, the cost of single crystalline solar cell devices is highly relay on the raw material in turn, Si itself. Therefore many researchers make an effort to reduce the amount of Si in solar cell by decreasing the thickness of wafer. The minimum thickness for maintaining the light absorption to obtain the enough conversion efficiency is about 50㎛. In the last few decades, several methods have been introduced to obtain thin Si layers without kerf-loss such as epitaxial layer transfer process, hydrogen implantation process, exfoliation process. However, these methods have many problems to overcome. Epitaxial layer transfer process is too complicate to low the yield, because of consisting with wet process for the formation of the release layer and CVD process for the formation of the Si epitaxial layer. Slimily, hydrogen implantation process is the high cost process, because of using the ultra-high vacuum ion implantation. Exfoliation process usually requires high temperature annealing process or high adhesive seed layer by the physical vapor deposition (PVD), so that it lead to the degradation of the life time of detached Si by high temperature and the increase of manufacturing cost. In this dissertation, a thin c-Si layer with a thickness of 50μm was successfully detached in all wet-process by replacing glue and seed deposition from the vacuum process to wet process. To achieve this, a high adhesive Ni seed layer on top of prepared nano-holes surface of Si substrate was applied with electroless deposition method. Also, obtained thin Si layer was utilized for fabrication of solar cell, and the conversion efficiency of this device was confirmed.