Defect structures in amorphous Germanium films

Abstract

The structures of 100 Å thick films of amorphous Ge ion implanted with 74Ge with energies of 10, 20, and 40 keV, and dosages of 3 × 1014 to 1015 ions/cm2, are determined by high energy electron diffraction and microscopy. Films bombarded with ion energies greater than 20 keV show a microstructure consisting of widely spaced pores having a maximum diameter of 100 Å. The presence of these pores is found to be independent of the substrate (NaCl and collodion coated glass), but dependent on film thickness. These large pores are not observed for the lower implantation energies. For low energy implantation and high dosages the reduced intensity function showed a considerable decrease in the intensity of the second interference peak as well as different low angle scattering. To interpret these results the concept of monovacaneies and divacancies is defined for the amorphous structures, and it is shown that the structure of these ion implanted films can be adequately described as a random network containing a uniform distribution of these point imperfections. Copyright © 1978 WILEY‐VCH Verlag GmbH & Co. KGaA