Formation of nanocrystallites in amorphous silicon thin films

Abstract

The formation of nanometer-sized silicon grains is reported using the crystallization of amorphous silicon (a-Si) thin films on single crystalline silicon (c-Si) substrates by a thermal annealing process. X-ray diffraction (XRD) measurements indicate grain diameters of 3 to 10 nm depending on the annealing conditions. The crystallization in the as-deposited a-Si thin films consists of a substrate induced epitaxial growth process forming crystalline Si collums and a second strain-induced crystallization process in the space between those columns forming nanocrystalline regions. The crystallized thin films show intense blue photoluminescence (PL) at room temperature. PL spectra of different crystallized a-Si thin films have different features.