A N CHAKRAVARTI

K P GHATAK

K K GHOSH

S GHOSH

A DHAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

physica status solidi (b)

In this paper, we study the Debye screening length (DSL) in ultrathin films of optoelectronic materials in the presence of light waves. The solution of the Boltzmann transport equation on the basis of the newly formulated electron dispersion laws will introduce new physical ideas and experimental findings under different external conditions. It has been found, taking ultrathin films of n-Hg1-xCdxTe, as an example, that the respective two-dimensional (2D) DSL in the aforementioned materials exhibits decreasing quantum step dependence with the increasing film thickness, surface electron concentration, light intensity and wavelength, respectively, with different numerical values. The nature of the variations is totally band structure dependent which is influenced by the presence of the different energy band constants. The strong dependence of the 2D DSL on both the light intensity and the wavelength reflects the direct signature of the light waves. The well-known result for the 2D DSL for nondegenerate wide gap materials in the absence of any field has been obtained as a special case of the present analysis under certain limiting conditions and this compatibility is the indirect test of our generalized formalism. Besides, we have suggested an experimental method of determining the 2D DSL in ultrathin materials in the presence of light waves having arbitrary dispersion laws. © 2008 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

Influence of light on the Debye screening length in ultrathin films of optoelectronic materials

We study theoretically the influence of light waves on the thermoelectric power under large magnetic field (TPM) for III-V, ternary and quaternary materials, whose unperturbed energy-band structures, are defined by the three-band model of Kane. The solution of the Boltzmann transport equation on the basis of this newly formulated electron dispersion law will introduce new physical ideas and experimental findings in the presence of external photoexcitation. It has been found by taking n-InAs, n-InSb, n-Hg 1-xCdx Te and n-In1-xGaxAs yP1-y lattice matched to InP as examples that the TPM decreases with increase in electron concentration, and increases with increase in intensity and wavelength, respectively in various manners. The strong dependence of the TPM on both light intensity and wavelength reflects the direct signature of light waves that is in direct contrast as compared with the corresponding bulk specimens of the said materials in the absence of external photoexcitation. The rate of change is totally band-structure dependent and is significantly influenced by the presence of the different energy-band constants. The well-known result for the TPM for nondegenerate wide-gap materials in the absence of light waves has been obtained as a special case of the present analysis under certain limiting conditions and this compatibility is the indirect test of our generalized formalism. Besides, we have also suggested the experimental methods of determining the Einstein relation for the diffusivity:mobility ratio, the Debye screening length and the electronic contribution to the elastic constants for materials having arbitrary dispersion laws. © 2008 WILEY-VCH Verlag GmbH &amp; Co. KGaA.

Annalen der Physik (Leipzig)

Influence of light waves on the thermoelectric power under large magnetic field in III-V, ternary and quaternary materials

We study the electron energy spectrum and the Debye screening length (DSL) for III-V, ternary, and quaternary materials in the presence of light waves, whose unperturbed energy band structures are defined by the three-band model of Kane. The solution of the Boltzmann transport equation on the basis of this newly formulated electron dispersion law will introduce new physical ideas and experimental findings in the presence of external photoexcitation. It has been found taking n -InAs, n -InSb, n -Hg1-x Cdx Te, and n -In1-x Gax Asy P1-y lattice matched to InP, as examples that the DSL decreases with the increase in electron concentration, intensity, and wavelength, respectively in various manners. The strong dependence of the DSL on both light intensity and wavelength reflects the direct signature of light waves which is in contrast as compared with the corresponding bulk specimens of the said materials in the absence of external photoexcitation. The rate of change is totally band structure dependent and is significantly influenced by the presence of the different energy band constants. The classical DSL equation in the absence of light waves has been obtained as a special case of the present analysis under certain limiting conditions and this compatibility is the indirect test of our generalized formalism. We have also suggested an experimental method of determining the DSL in degenerate materials having arbitrary dispersion laws. © 2007 American Institute of Physics.

Fulltext

Journal of Applied Physics

Influence of light on the Debye screening length in III-V, ternary, and quaternary materials

We study theoretically the thermoelectric power in the presence of a large magnetic field (TPM) in heavily doped III-V, II-VI, PbTe/PbSnTe, strained layer and HgTe/CdTe quantum dot superlattices (QDSLs) with graded structures on the basis of newly formulated electron energy spectra and compare the same with that of the constituent materials. It has been found, taking heavily doped GaAs/Ga1-xAlxAs, CdS/CdTe, PbTe/PbSnTe, InAs/GaSb and HgTe/CdTe QDSLs as examples, that the TPM increases with increasing inverse electron concentration and film thickness, respectively, in different oscillatory manners and the nature of oscillations is totally band structure dependent. We have also suggested the experimental methods of determining the Einstein relation for the diffusivity-mobility ratio, the Debye screening length and the electronic contribution to the elastic constants for materials having arbitrary dispersion laws. © 2006 Elsevier B.V. All rights reserved.

Physica E: Low-Dimensional Systems and Nanostructures

Simple theoretical analysis of the thermoelectric power in quantum dot superlattices of non-parabolic heavily doped semiconductors with graded interfaces under strong magnetic field

Journal	physica status solidi (b)
Publisher	-
ISSN	0370-1972