D MUKHERJI

A N CHAKRAVARTI

B R NAG

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 (a)

We study the Einstein relation for the diffusivity to mobility ratio (DMR) in quantum wires (QWs) of 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. It has been found, taking n-InAs, n-InSb, n- Hg1-x Cdx Te, n- In1-x Gax Asy P1-y lattice matched to InP as examples, that the respective DMRs exhibit decreasing quantum step dependence with the increasing film thickness, decreasing electron statistics, increasing light intensity and wavelength, with different numerical values. The nature of the variations is totally band structure dependent and is influenced by the presence of the different energy band constants. The strong dependence of the DMR on both the light intensity and the wavelength reflects the direct signature of the light waves which is in contrast as compared to the corresponding QWs of the said materials in the absence of photoexcitation. The classical equation of the DMR in the absence of any field has been obtained as a special case of the present analysis under certain limiting conditions and this is the indirect test of the generalized formalism. We have suggested an experimental method of determining the DMR in QWs of degenerate materials having arbitrary dispersion laws and our results find six applications in the field of quantum effect devices. © 2008 American Institute of Physics.

Fulltext

Journal of Applied Physics

The Einstein relation in quantum wires of III-V, ternary, and quaternary materials in the presence of light waves: Simplified theory, relative comparison, and suggestion for experimental determination

We study theoretically the energy spectrum of the conduction electrons and the Einstein relation for the diffusivity-mobility ratio (DMR) for III-V, ternary and quaternary materials, whose unperturbed energy band structures are defined by the three-band model of Kane, in the presence of light waves. 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 under different external conditions. It has been observed that the unperturbed isotropic energy spectrum in the presence of light changes into an anisotropic dispersion relation with the energy-dependent mass anisotropy. It has been found taking n-InAs, n-InSb, n-Hg1-xCdxTe and n-In1-xGaxAsyP1- y lattice matched to InP, as examples that the DMR increases with increasing electron concentration, decreasing with increasing intensity and wavelength in various manners. The rate of change is totally band structure dependent and is influenced by the presence of the different energy band constants. The well-known result for the DMR for degenerate 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 suggested an experimental method of determining the DMR in degenerate materials having arbitrary dispersion laws. © 2007 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

Influence of light on the Einstein relation in III-V, ternary and quaternary materials: Simplified theory and a suggestion for experimental determination

In this paper an attempt is made to study the Einstein relation for the diffusivity-mobility ratio (DMR) in nonlinear optical compounds on the basis of a newly formulated electron energy spectrum taking into account the combined influences of the anisotropies in the effective electron mass and the spin orbit splitting constant together with the inclusion of crystal field splitting in the Hamiltonian within the framework of k.p formalism. The corresponding results for III-V, ternary and quaternary types of optoelectronic materials form a special case of our generalized analysis. We have also studied the DMR in II-VI, Bi, IV-VI and stressed materials on the basis of various band models as applicable for such specialized materials. It has been found taking n-Cd3As2, n-CdGeAs2, n-InAs, n-InSb, n-Hg1-xCdxTe and n-In1-xGaxAsyP1-y lattice matched to InP, CdS, Bi, PbS, PbTe, PbSe and stressed InSb as examples of the aforementioned compounds that the DMR increases with increasing electron concentration in various manners and the rate of increase is greatly influenced by the presence of the different energy band constants of the said materials together with the fact that the rates of variation are totally band structure dependent. An experimental method of determining the DMR in degenerate samples having arbitrary dispersion laws has been suggested and the present simplified analysis is in agreement with the suggested relationship. In addition, the well-known results for nondegenerate wide gap materials have been obtained as special cases of our generalized theory under certain limiting conditions. © 2006 Elsevier B.V. All rights reserved.

The Einstein relation for the diffusivity-mobility ratio in nonlinear optical, optoelectronic and the related materials

An attempt is made to study the Einstein relation for the diffusivity-mobility ratio (DMR) in quantum wells (QWs) and quantum well wires (QWWs) of tetragonal compounds on the basis of a newly formulated electron energy spectrum taking into account the combined influences of the anisotropies in effective electron mass, the spin-orbit splitting, and the presence of crystal field splitting, respectively. The results for quantum-confined III-V compounds form a special case of our generalized analysis. The DMR has also been studied for QWs and QWWs of II-VI and IV-VI materials. Taking QWs and QWWs of CdGeAs2, InAs, CdS and PbSe as examples, it was found that the DMR increases with increasing carrier statistics and decreasing film thickness respectively in various oscillatory manners emphasizing the influence of dimensional quantizations and the energy band constants in different cases. An experimental method of determining the DMR in nanostructures with arbitrary dispersion laws has also been suggested and the present simplified analysis is in agreement with the suggested relationship. The well-known results for nanostructures with parabolic energy bands have also been obtained as special cases from this generalized analysis under certain limiting conditions.

Electrical Engineering

The Einstein relation in nanostructured materials: Simplified theory and suggestion for experimental determination

An attempt is made to study the carrier contribution to the elastic constants in semiconductor superlattices and the constituent materials under cross-field configuration in the presence of spin and broadening. It is found, taking Ga1-xAlxAs/ALAs superlattice as an example that the said contribution increases with increasing carrier degeneracy, oscillates with the reciprocal quantizing magnetic field and the cross-field configuration enhances the numerical values. The carrier contribution to the second and third order elastic constants in semiconductor superlattices is larger as compared to the constituent materials. An experimental method is suggested for determining the carrier contribution to the elastic constants in degenerate materials having arbitrary dispersion laws. In addition, the corresponding well-known results for degenerate wide gap materials in the absence of any fields are also obtained from the generalized expressions under certain limiting conditions. Copyright © 1996 Elsevier Science Ltd.

Journal of Physics and Chemistry of Solids

On a simplified analysis of the carrier contribution to the elastic constants in semiconductor superlattices in the presence of crossed electric and quantizing magnetic fields

Journal	physica status solidi (a)
Publisher	-
ISSN	0031-8965