OPTICAL DETERMINATION OF THE MASS DENSITY OF AMORPHOUS AND MICROCRYSTALLINE SILICON LAYERS WITH DIFFERENT HYDROGEN CONTENTS

We have measured the density of amorphous and microcrystalline silicon films using an optical method. The mass density decreases with increa sing hydrogen content, consistent with a hydrogenated di-vacancy model that fits the data for amorphous silicon. Material produced by hot wi re assisted chemical vapour deposition, with low hydrogen content, has a higher density and is structurally different from glow discharge ma terial with hydrogen content around 10 at.%. The lower density microcr ystalline silicon seems to be porous. (C) 1998 Elsevier Science B.V. A ll rights reserved.