Nanocrystal seeding: A low temperature route to polycrystalline Si films

Abstract

A novel method is presented for growth of polycrystalline silicon films on amorphous substrates at temperatures of 540-575°C. Grain nucleation and grain growth are performed in two steps, using Si nanocrystals as nuclei ("seeds"). The nanocrystal seeds are produced by excimer laser photolysis of disilane in a room temperature flow cell. Film (grain) growth occurs epitaxially on the seeds in a separate thermal chemical vapor deposition (CVD) step, with growth rates 10-100 times higher than similar CVD growth rates on crystal Si. Grain size and CVD growth rates are dependent on seed coverage, for seed coverage <0.2 monolayers.