A study of polycrystalline silicon thin films as a seed layer in liquid phase epitaxy using aluminum-induced crystallization

Abstract

In this paper, the making of polycrystalline silicon thin films as a seed layer for thicker polycrystalline thin film Si solar cells was investigated. The seed layer was crystallized using Aluminum-induced crystallization (AIC) in various process conditions in order to determine the optimized process parameters of AIC. The layer exchange process and the a-Si crystallization during AIC (annealing at 500 °C, 1 h) were observed. The crystallized and continuous poly-Si thin films were formed with the same thickness as Al layers. However, as the thickness of Al decreased, a continuous film became thinner and more protrusions were observed at film surface. The grain size of crystallized Si thin films ranged from 2000 Å to more than 1 μm. The hole concentration, Hall mobility, and resistivity were 3.79–7.00×10 18 cm −3 , 19.9–36.5 cm 2 /Vs, and 0.037–0.045 Ω cm , respectively. These results indicate that the fabrication of poly-Si thin films using AIC is an industrially relevant techniques because of low-temperature process and short processing time. The crystallized film with grains more than 2000 Å will be a good candidate of seed layers for liquid phase epitaxy.