IN-SITU STUDY OF THE INTERFACES BETWEEN PLASMA-DEPOSITED AMORPHOUS-SILICON AND SILICON DIOXIDE BY UV-IR SPECTROELLIPSOMETRY

An in situ ellipsometry study of the interfaces between plasma-deposit ed amorphous silicon (a-Si:H) and silicon dioxide (a-SiO2) is presente d. In order to achieve a more detailed description of the interface fo rmation, measurements obtained by UV-visible and infrared (IR) spectro ellipsometry are combined. Intermixing layers, about 30-40 Angstrom th ick, are clearly revealed at the interface independent of the depositi on sequence used. In particular, the presence of SiO and (O)SiHn bonds in the first few monolayers of the growth of the ''top'' a-Si:H is id entified. Likewise, hydrogen accumulation, revealed by SiH vibrations, is observed during the early stage of the growth of a-SiO2 on top of a-Si:H. The behaviours of the a-Si:H-a-SiO2 and a-Si:H-a-SiNx interfac es are compared.