STRUCTURAL TRANSFORMATIONS OF AS-DOPED POLYCRYSTALLINE SILICON LAYERS USED AS EMITTER CONTACTS

The epitaxial realignment of As-doped polycrystalline layers has been investigated in structured substrates. Rectangular strips of width in the 0.2-100 mu m range were used. The realignment starts by nucleation of epitaxial columns at grain boundaries in contact with the poly-Si/substrate interface. In the 1-100 mu m strips the realignment proceeds by two-dimensional growth, while in the 0.2-0.3 mu m strips by one-dimensional growth. The growth kinetics are slowed down in the small width geometry and the thermal budget needed to realign the films increases.