Abstract
Ultrathin crystalline silicon (c-Si) and amorphous silicon (a-Si:H) films have been prepared using plasma-enhanced chemical vapor deposition (PECVD) and atomic hydrogen etching methods. The complex dielectric functions (2 < hv < 4.5 eV) of films consisting of isolated clusters have been measured in situ and in real time using spectroscopic ellipsometry. For 12 Å c-Si cluster films, a sharp absorption onset is observed near 3 eV that blue-shifts with decreasing thickness, in consistency with the quantum confinement of electrons. A much broader absorption onset, observed for ~13 Å a-Si:H cluster films near 2 eV, is attributed to an electron mean free path that is less than the cluster size, which limits the appearance of confinement effects.
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Collins, R.W., Nguyen, H.V., An, I. et al. Preparation and Optical Properties of Ultrathin Silicon Films. MRS Online Proceedings Library 358, 763 (1994). https://doi.org/10.1557/PROC-358-763
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DOI: https://doi.org/10.1557/PROC-358-763