The Structure of Amorphous Semiconductors.

X-ray and electron diffraction techniques were used to determine the atomic arrangements in a series of vitreous Se-As alloys containing from 0-50 As. The x-ray work was performed on bulk samples quenched from the melt. The electron diffraction work was performed on thin films sputtered from bulk targets. The electron diffraction was carried out with 50,000 V electrons in an apparatus fitted with an energy selection system which eliminated the inelastic scattering. The inelastic scattering was also analyzed and interpreted in terms of the optical constants. Thus, in addition to the atomic arrangements, it was possible to obtain information on the nature of the bonding mechanisms in these amorphous materials. A Monte Carlo technique was developed to interpret the structures of these materials. In the most successful approach, the appropriate number of Se and As Atoms were placed at random, and atomic positions were varied until a satisfactory correlation was obtained with the measured radial distribution function. The resultant atomic arrangements were then examined visually. Author