Evidence of Voids Within the As-Deposited Structure of Glassy Silicon

We present electron diffraction data from amorphous silicon which cannot be reconciled with the intensity profiles derived from small-crystallite models based on the diamond structure. Our diffraction patterns do reveal a pronounced low-angle scattering which anneals out on progressive heating and is indicative of actual void spaces, or regions of distinctly deficient density, in the films. These regions may be responsible for the recent observations of Brodsky and Title on surface states within the bulk of amorphous Si.