scholarly journals A Brief Study to Clarify Some Aspects Related to Vibrational Density of States for the Far Infrared Range in Amorphous Semiconductors

1998 ◽  
Vol 20 (3) ◽  
pp. 143-145 ◽  
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro
Keyword(s):  
Optical Absorption ◽  
Density Of States ◽  
Far Infrared ◽  
Structural Disorder ◽  
Amorphous Semiconductors ◽  
Infrared Range ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Vibrational Density Of States ◽  
Vibrational Density

Phonon density of states of amorphous semiconductors for the far-infrared range is examined analytically. On the basis of this formulation, optical absorption corresponding to structural disorder is evaluated and discussed at the far-infrared range for a-Ge and a-Si.

A MODEL FOR OPTICAL ABSORPTION OF AMORPHOUS GaAs IN THE FAR-INFRARED RANGE BY USING AN OPERATIONAL TECHNIQUE

1999 ◽  
Vol 13 (25) ◽  
pp. 919-923 ◽  
Author(s):  
M. A. GRADO-CAFFARO ◽  
M. GRADO-CAFFARO
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficient ◽  
Far Infrared ◽  
Structural Disorder ◽  
Optical Absorption Coefficient ◽  
Infrared Range ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Operational Technique ◽  
Dynamical Disorder

By considering a sample of amorphous GaAs with a small zone of dynamical disorder, an expression for the optical absorption coefficient and phonon density of states in the low region of the far-infrared range is obtained. To get to this end, absorption corresponding to structural disorder is neglected.

MAXIMUM DYNAMICAL DISORDER IN AMORPHOUS GaAs

1994 ◽  
Vol 08 (03) ◽  
pp. 169-172 ◽  
Author(s):  
M.A. GRADO CAFFARO ◽  
M. GRADO CAFFARO
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficient ◽  
Density Of States ◽  
Far Infrared ◽  
Conduction Band Edge ◽  
Infrared Range ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Low Frequencies ◽  
Dynamical Disorder

Maximum dynamical disorder in amorphous gallium arsenide is investigated in a special way. In particular, this maximum disorder refers to distance and it is investigated in the context of optical absorption at very low frequencies in the far-infrared range when the photon energy is larger than 2Ec, Ec being the energy at the conduction band edge. Absorption coefficient is calculated and compared with experimental work. Phonon density of states is also evaluated.

A Semi-Quantitative Analysis of Far-Infrared Absorption in Dynamically Disordered Gallium Arsenide

2003 ◽  
Vol 17 (13n14) ◽  
pp. 783-787 ◽  
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro
Keyword(s):  
Experimental Data ◽  
Quantitative Analysis ◽  
Optical Absorption ◽  
Density Of States ◽  
Infrared Absorption ◽  
Mathematical Expression ◽  
Far Infrared ◽  
Structural Disorder ◽  
Infrared Range ◽  
Electronic Density

A mathematical expression for the coefficient of optical absorption in amorphous GaAs referred to the far-infrared range is obtained by neglecting the spectrum contribution corresponding to structural disorder. In addition, our results are compared with experimental data and several aspects related to the electronic density of states are discussed.

scholarly journals Some New Results on Vibrational Properties of Amorphous Group IV Semiconductors

1993 ◽  
Vol 16 (1) ◽  
pp. 65-68
Author(s):  
M. A. Grado Caffaro ◽  
M. Grado Caffaro
Keyword(s):  
Density Of States ◽  
Structure Factor ◽  
Dynamic Structure ◽  
Structural Disorder ◽  
Group Iv ◽  
Dynamic Structure Factor ◽  
Vibrational Properties ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Group Iv Semiconductors

For neutron scattering, an interesting formula is derived from the coherent one-phonon dynamic structure factor. In this derivation, phonon density of states is involved; this density is related to spectra due to structural disorder, which is investigated. Our considerations refer to amorphous Group IV semiconductors.

NEW RESULTS ON OPTICAL ABSORPTION IN AMORPHOUS CADMIUM OXIDE FOR THE VISIBLE RANGE: A THEORETICAL APPROACH

2004 ◽  
Vol 18 (24) ◽  
pp. 1255-1259 ◽  
Author(s):  
M. A. GRADO-CAFFARO ◽  
M. GRADO-CAFFARO
Keyword(s):  
Experimental Data ◽  
Optical Absorption ◽  
Band Gap ◽  
Density Of States ◽  
Theoretical Approach ◽  
Cadmium Oxide ◽  
Visible Region ◽  
Visible Range ◽  
Phonon Density ◽  
Phonon Density Of States

Optical absorption of amorphous cadmium oxide in the visible region is investigated by considering the band-gap shift experienced by this material. At the same time, influence of oxygen partial pressure is studied so that new results related to absorption in the visible margin are obtained; these results agree well with experimental data. In addition, phonon density of states and its shift due to the band-gap shift are evaluated.

scholarly journals A Discussion on the Phonon Density of States of Amorphous Germanium for the Infrared Range

1998 ◽  
Vol 21 (1) ◽  
pp. 53-56
Author(s):  
M. A. Grado-Caffaro ◽  
M. Grado-Caffaro
Keyword(s):  
Density Of States ◽  
Harmonic Approximation ◽  
Infrared Range ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
Theoretical Formulation ◽  
Amorphous Germanium

A theoretical formulation for the phonon density of states of amorphous germanium in the infrared range is proposed. This formulation is based upon the quasi-harmonic approximation and is compared with previous results.

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