STRUCTURE OF SILICON-NITRIDE LAYERS GROWN BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

Thin silicon nitride layers are grown on GaAs(100) substrates by plasm a-enhanced chemical vapor deposition from hexamethyldisilazane (HMDS) or its mixtures with NH3 and characterized by ellipsometry, IR spectro scopy, scanning electron microscopy, synchrotron x-ray diffraction, an d electrical measurements. The layers grown from HMDS are polycrystall ine and consist of hexagonal silicon nitride and considerable amounts of hexagonal silicon carbide. In the presence of NH3, the layers grow free from SiC and show (220) or (200) preferential orientation, depend ing on growth conditions.