Assessment of the coherent potential approximation for the absorption spectra of a one-dimensional Frenkel exciton system with a Gaussian distribution of fluctuations in the optical transition frequency

2015 ◽  
Vol 65 ◽  
pp. 141-143 ◽  
Author(s):  
A. Boukahil ◽  
I. Avgin ◽  
D.L. Huber
Keyword(s):  
Absorption Spectra ◽  
Gaussian Distribution ◽  
Optical Transition ◽  
Coherent Potential Approximation ◽  
Transition Frequency ◽  
Frenkel Exciton ◽  
Potential Approximation ◽  
One Dimensional ◽  
Exciton System

Optical Properties of a Quantum Well of A1−x Bx Alloy Semiconductor in the Coherent Potential Approximation

2000 ◽  
Vol 639 ◽  
Author(s):  
Yuzo Shinozuka ◽  
Hirotsugu Kida ◽  
Masanori Watarikawa
Keyword(s):  
Optical Properties ◽  
Quantum Well ◽  
Tight Binding ◽  
Impurity Band ◽  
Coherent Potential Approximation ◽  
Electron Hole ◽  
Potential Approximation ◽  
Binding Model ◽  
Rectangular Array ◽  
One Dimensional

ABSTRACTWe have theoretically studied optical properties of a quantum well (QW) in which the well region is constructed from a binary alloy semiconductor A1−xBx in the coherent potential approximation (CPA). A tight binding model is used for a single particle (electron, hole, Frenkel exciton) in the well composed by a rectangular array of NxxNyxNz sites. The effect of the diagonal randomness is reduced to the coherent potential σ(E), which is assumed to be the same for all sites, and is selfconsistently determined with the average Green's function. For a slab (∞, ∞, Nz) and wire (∞, Ny, Nz), the density of states (E) is composed of Nz (or NyxNz) subbands, each shows the two (one)-dimensional van-Hove singularity. When x (or 1−x) is small, a B (A) impurity-band always appears at the lower (higher) energy side of the lowest (highest) host-band. The change of (E) and the absorption spectrum by changing the well-width and the dimensionality is discussed in detail.

scholarly journals Absorption Spectrum and Density of States of Square, Rectangular, and Triangular Frenkel Exciton Systems with Gaussian Diagonal Disorder

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Ibrahim Avgin ◽  
David Huber
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Elliptic Integral ◽  
Coherent Potential Approximation ◽  
Square Lattice ◽  
Integral Approach ◽  
Frenkel Exciton ◽  
Potential Approximation ◽  
Effects Of Disorder ◽  
Diagonal Disorder

Using the coherent potential approximation, we investigate the effects of disorder on the optical absorption and the density of states of Frenkel exciton systems on square, rectangular, and triangular lattices with nearest-neighbor interactions and a Gaussian distribution of transition energies. The analysis is based on an elliptic integral approach that gives results over the entire spectrum. The results for the square lattice are in good agreement with the finite-array calculations of Schreiber and Toyozawa. Our findings suggest that the coherent potential approximation can be useful in interpreting the optical properties of two-dimensional systems with dominant nearest-neighbor interactions and Gaussian diagonal disorder provided the optically active states are Frenkel excitons.

Coherent potential approximation for the absorption spectra of a two-dimensional Frenkel exciton system with Gaussian diagonal disorder

2014 ◽  
Vol 28 (32) ◽  
pp. 1450251 ◽  
Author(s):  
A. Boukahil ◽  
D. L. Huber
Keyword(s):  
Density Of States ◽  
Reasonable Agreement ◽  
Nearest Neighbor ◽  
Square Lattice ◽  
Two Dimensional ◽  
Frenkel Exciton ◽  
Potential Approximation ◽  
Urbach Tail ◽  
Diagonal Disorder ◽  
Exciton System

We investigate the optical absorption and the density of states of a Frenkel exciton system on a square lattice with nearest-neighbor interactions and a Gaussian distribution of transition frequencies (i.e. Gaussian diagonal disorder). Results are presented for the absorption and the density of states of direct and indirect edge systems for a range of variances. There is reasonable agreement with the corresponding finite array calculations of Schreiber and Toyozawa. The existence of an Urbach tail is also investigated.

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