Energy gaps in amorphous covalent semiconductors

Abstract

Abstract. A calculation of approximate density of states for a disordered covalent semiconductor shows that the energy gap is due to the presence of short range order.

Determination of optical constants: Amorphous carbon

“…Therefore, the results support the assumption of semiconducting behaviour in non-annealed carbon films (10,11). Comparison with the calculated density of states (12) however is impossible because nothing is known concerning the oscillator 7 photon energy ( e Vl --strengths of the different transitons between localized states within the band gap of llamorphous diamond". The structure near 3.5 e V is too weak to be interpreted within the framework of critical points.…”

Selfconsistent single‐site approximation for structurally disordered solids

“…There are also cluster methods, which allow for the calculation of the DOS of long range disordered systems taking into account the effects typical for the SRO by assuming clusters of muffin-tin potentials distributed randomly [ 5 ] . On the other side there are selfconsistent methods based on the single-site approximation only for calculating electronic spectra of liquids with no SRO.…”

“…The generalization of the latter [4] yields a complex energy band scheme (CBS), which is very convenient for the investigation of electronic spectra of real disordered materials as, for instance, amorphous Geor Si-films. There are also cluster methods, which allow for the calculation of the DOS of long range disordered systems taking into account the effects typical for the SRO by assuming clusters of muffin-tin potentials distributed randomly [ 5 ] . On the other side there are selfconsistent methods based on the single-site approximation only for calculating electronic spectra of liquids with no SRO.…”

The Use of Clusters of Atoms in the Calculation of Electronic Structures

“…The cluster model as used by Johnson [I] and the groups at Massachusetts Institute of Technology and the University of Florida focus attention on discrete bound states, here I want to present a further part of the theory where the energy range of interest is in the continuum, above muffin-tin zero. The basic theory was developed independently at the University of Bristol using a formalism due to Lloyd [2] and Klima and McGill [3] first applied it to a cluster of atoms in a model of amorphous semiconducting materials.…”