Crystallization at initial stage of low-temperature polycrystalline silicon growth using ZnS buffer layer with 〈111〉 preferred orientation

Abstract

We developed a low-temperature growth technique for polycrystalline silicon (poly-Si). When Si is deposited on glass substrates at 450 °C, it crystallizes as thickness increases, but 10-nm-thick layers of Si are mainly amorphous. Use of a ZnS buffer layer with 〈111〉 preferred orientation facilities crystallization of Si during the initial growth stages. The preferred orientation of poly-Si on glass substrates is 〈110〉, while that of poly-Si on the ZnS buffer layer is 〈111〉. This is probably due to local epitaxial growth on polycrystalline ZnS grains with 〈111〉 preferred orientation. Raman spectroscopy showed that the ZnS buffer layer significantly improved the crystallinity of 25-nm-thick Si layers.