Density of localized states in disordered solids

Journal Article · Sun Aug 01 04:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.3100· OSTI ID:6325377

Klochikhin, A A; Ogloblin, S G ^[1]

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1. Petersburg Nuclear Physics Institute, Gatchina, 188350 St. Petersburg (Russian Federation)

Calculations of a localized state density (DOS) are carried out in the framework of a well-known variant of the Anderson model, i.e., for the three-dimensional single-band Hamiltonian with diagonal disorder. Results of the calculations give three regions of the energies below the virtual crystal band edge [ital E][sub [ital G]][sup vc] characterized by different behavior of the DOS. (I) The band-edge (BE) region is placed in the vicinity of [ital E][sub [ital G]][sup vc]. Here the DOS on a linear scale is approximately a linear function of the localization energy. (II) At lower energies the Urbach law governs the DOS behavior. (III) At lower energies the DOS exhibits Lifshitz singularity dependence. Here the DOS has a very small value and rare deep centers (DC) can appear in the spectrum. The problem of the DC-band inhomogeneous broadening is also considered. Estimations of the number of localized states and of the mobility-edge position are presented. The data on single-electron-DOS energy dependence of [alpha]-Si:H are used to compare qualitatively the calculated DOS with the experiment results. Good agreement is reached both in DOS behavior and in the mobility-edge location. An aspect in the approach to the problem is an additional restriction of the trial-function class minimizing the one-instanton action. The additional restriction was obtained from the analysis of the localized state problem for the concrete realizations of the disordered system under consideration. A strong-scattering problem in the limit of small concentration of scatterers is studied, as well as the case of the three-component system consisting of a binary solution of weak scatterers with a third component comprising rare deep centers. In all of the cases considered the general expressions for the DOS including prefactors are found, as well as their approximate forms.

• OSTI ID: 6325377
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:5; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

665000* -- Physics of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY-LEVEL DENSITY
HYDROGEN ADDITIONS
SEMIMETALS
SILICON
SOLIDS