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A K Dasgupta

Bio: A K Dasgupta is an academic researcher from Sammilani Mahavidyalaya. The author has contributed to research in topics: Electronic band structure & Light intensity. The author has an hindex of 2, co-authored 2 publications receiving 26 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a simple theoretical analysis of the effective electron mass (EEM) at the Fermi level for III-V, ternary and quaternary materials, on the basis of a newly formulated electron energy spectra in the presence of light waves whose unperturbed energy band structures are defined by the three-band model of Kane, is presented.
Abstract: We present a simple theoretical analysis of the effective electron mass (EEM) at the Fermi level for III–V, ternary and quaternary materials, on the basis of a newly formulated electron energy spectra 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 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 In the presence of light, the conduction band moves vertically upward and the band gap increases with the intensity and colours of light 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 EEM increases with increasing electron concentration, intensity and wavelength in various manners The strong dependence of the effective momentum mass (EMM) at the Fermi level on both the light intensity and wavelength reflects the direct signature of the light waves which is in contrast with the corresponding bulk specimens of the said materials in the absence of photo-excitation 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 EEM at the Fermi level 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

23 citations

Journal ArticleDOI
TL;DR: In this article, the diffusivity-mobility ratio (DMR) in ultra-thin films of III-V, ternary and quaternary materials in the presence of light waves, whose unperturbed energy band structures are defined by the three-band and two band models of Kane together with parabolic energy bands, was studied.
Abstract: In this paper, we study the Einstein relation for the diffusivity-mobility ratio (DMR) in ultra-thin films of III-V, ternary and quaternary materials in the presence of light waves, whose unperturbed energy band structures are defined by the three-band and two band models of Kane together with parabolic energy bands. 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-InAs, n-InSb, n-Hg1-xCdxTe,n-In1-xGaxAsyP1-y lattice matched to InP, as examples, that the respective DMR in the aforementioned materials exhibits decreasing quantum step dependence with the increasing film thickness, decreasing electron statistics, increasing light intensity and wavelength, with different numerical values. The DMR decreases with increasing alloy composition and the nature of the variations are totally band structure dependent which 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 with the corresponding ultrathin films of the said materials in the absence of photo-excitation. The well-known result for the DMR for degenerate 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 DMR in ultrathin materials in the presence of light waves having arbitrary dispersion laws.

8 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors studied thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials.
Abstract: We study thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials. The corresponding results for QWs of III-V, ternary, and quaternary compounds form a special case of our generalized analysis. The TPM has also been investigated in QWs of II-VI, IV-VI, stressed materials, n-GaP, p-PtSb2, n-GaSb, and bismuth on the basis of the appropriate carrier dispersion laws in the respective cases. It has been found, taking QWs of n-CdGeAs2, n-Cd3As2, n-InAs, n-InSb, n-GaAs, n-Hg1?xCdxTe, n-In1?xGaxAsyP1?y lattice-matched to InP, p-CdS, n-PbTe, n-PbSnTe, n-Pb1?xSnxSe, stressed n-InSb, n-GaP, p-PtSb2, n-GaSb, and bismuth as examples, that the respective TPM in the QWs of the aforementioned materials exhibits increasing quantum steps with the decreasing electron statistics with different numerical values, and the nature of the variations are totally band-structure-dependent. In CNTs, the TPM exhibits periodic oscillations with decreasing amplitudes for increasing electron statistics, and its nature is radically different as compared with the corresponding TPM of QWs since they depend exclusively on the respective band structures emphasizing the different signatures of the two entirely different one-dimensional nanostructured systems in various cases. The well-known expression of the TPM for wide gap materials has been obtained as a special case under certain limiting conditions, and this compatibility is an indirect test for our generalized formalism. In addition, we have suggested the experimental methods of determining the Einstein relation for the diffusivity-mobility ratio and the carrier contribution to the elastic constants for materials having arbitrary dispersion laws.

17 citations

Journal ArticleDOI
TL;DR: In this article, an attempt is made to study the two dimensional (2D) effective electron mass (EEM) in quantum wells (Qws), inversion layers (ILs) and NIPI superlattices of Kane type semiconductors in the presence of strong external photoexcitation on the basis of a newly formulated electron dispersion laws within the framework of k.p. formalism.

16 citations

Journal ArticleDOI
TL;DR: In this paper, a simple generalized theory is presented for the determination of interband optical absorption coefficient (IOAC) around band edges, in quantum well (QW) structure of non-parabolic semiconducting materials whose band structures obey the three band model of Kane.
Abstract: A simple generalized theory is presented for the determination of interband optical absorption coefficient (IOAC) around band edges, in quantum well (QW) structure of non-parabolic semiconducting materials whose band structures obey the three band model of Kane. The dependence of absorption coefficient on wave-vector (k→) has also been investigated. IOAC has been calculated for a wide range of III–V compound semiconductors, such as InAs, InSb, Hg1−xCdxTe, and In1−xGaxAsyP1−y lattice matched to InP. It has been found that IOAC for QWs increases in steps with increasing photon energy and the positions of jumps of the coefficient are more closely spaced in the three band model of Kane than those with parabolic energy band approximations in all the cases. IOAC for QWs is largely dependent on the polarization direction of the incident light and on the well dimension as well. The expressions of IOAC presented in this article can easily be extended to incorporate the effects of different external conditions like...

4 citations

Book ChapterDOI
01 Jan 2012
TL;DR: In this article, the authors have discussed many aspects of TPSM based on the dispersion relations of the nanostructures of different technologically important materials having different band structures in the presence of 1D, 2D, and 3D confinements of the wavevector space of the charge carriers, respectively.
Abstract: In this book, we have discussed many aspects of TPSM based on the dispersion relations of the nanostructures of different technologically important materials having different band structures in the presence of 1D, 2D, and 3D confinements of the wave-vector space of the charge carriers, respectively. In this chapter, we discuss few applications in this context in Sect. 14.2 and we shall also present a very brief review of the experimental investigations in Sect. 14.3 which is a sea in itself. Section 14.4 contains the single experimental open research problem.

4 citations

Journal ArticleDOI
TL;DR: In this article, a generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k→) dependence of the optical transition matrix element.
Abstract: A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k→) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg1−xCdxTe, and In1−xGaxAsyP1−y lattice matched to InP, as example of III–V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The re...

1 citations