Stress Originating From Nanovoids In Hydrogenated Amorphous Semiconductors

Structural inhomogeneities in the form of voids of nanometer sizes (nanovoids) have long been known to be present in hydrogenated amorphous semiconductors (Si, Ge). The physical and electrical properties of hydrogenated amorphous semiconductors can be pronouncedly influenced by the presence and characteristics of such nanovoids. In this work, by measuring in situ the intrinsic stress developments during deposition of pure, amorphous and of hydrogenated amorphous semiconductor (Si, Ge) thin films, under the same conditions in ultrahigh vacuum and on a comparative basis, a major source of tensile stress development could be ascribed to the occurrence of nanovoids in aSi: H and a-Ge: H. The measurements allowed a quantitative evaluation of the surface stress acting along the surface of the nanovoids: 1.1-1.9 N/m for a-Si: H and 0.9-1.9 N/m for a-Ge: H. Published by AIP Publishing.