On the structure of semiconducting amorphous systems

Abstract We present unique structural properties of amorphous semiconductors, for alloys like a-Ge x Sb 100− x , a-Ga x Te 100− x and for pure elements like a-C, a-Si, a-Ge. We observe, in all of them, a peak in the structure factor S ( K ) at scattering vectors K =2 k F , with 2 k F the diameter of the Fermi sphere (although free conducting electrons are absent) which is related to local spherical-periodic order in r -space. We discuss this structural feature as caused by an optimised resonance between the electronic and the static atomic structure (SAS) with subsequent consequences on structural stabilisation and electronic transport. In order to support the model we also present plasmon data.