An attempt is made to study the effective electron mass in strained layer superlattices of non-parabolic semiconductors with graded structures under sirong magnetic quantization and to compare the same with the bulk specimens of the constituent materials, by formulating the appropriate magneto-dispersion laws. It is found, taking InAs/GaSb superlattice as an example, that the effective electron mass oscillates with the inverse quantizing magnetic field due to the Shubnikov-de Hass effect. The dependence of the effective mass on the magnetic quantum number in addition to Fermi energy is an intrinsic property of such semiconductor heterostructures. The stress makes the mass quantum number dependent in bulk specimens and even in the presence of broadening, the effective masses in superlattices exhibit significant oscillations with enhanced numerical values from that of the constituent semiconductors. Besides the effective electron masses also increase in an oscillatory way with increasing electron c...

On the effective electron mass in strained layer superlattices of non-parabolic semiconductors under strong magnetic quantization

On the Thermoelectric Power in Superlattices of III–V Semiconductors under Magnetic Quantization

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

http://iopscience.iop.org/article/10.1088/0031-8949/75/6/012/pdf

A simple theoretical analysis of the effective electron mass in III-V, ternary and quaternary materials in the presence of light waves

We study the thermoelectric power of the electrons under magnetic quantization in III–V, II–VI, PbTe/PbSnTe and strained layer superlattices with graded interfaces and compare the same with the corresponding bulk specimens of the constituent materials by formulating the respective expressions incorporating the broadening. It is found, by taking GaAs/Ga1−x Al x As, CdS/CdTe, PbTe/PbSnTe and InAs/GaSb superlattices with graded interfaces as examples, that the thermoelectric power exhibits oscillatory dependence with the inverse quantizing magnetic field due to Shubnikov-de Hass effect and increases with decreasing electron concentration in an oscillatory manner in all the aforementioned cases. The thermopower in graded superlattices is greater than that of constituent bulk materials together with the fact that the oscillations in superlattices show up much more significantly as compared to the respective constituent materials. In addition, the well-known expressions for bulk specimens of wide-gap semiconductors have also been obtained as special cases from our generalized expressions under certain limiting conditions.

Thermoelectric power in superlattices of nonparabolic semiconductors with graded interfaces under magnetic quantization

An attempt is made to study the Einstein relation for the diffusivity‐mobility ratio of the electrons in degenerate n‐type small‐gap semiconductors under strong magnetic field on the basis of three‐band Kane model without any approximations of band parameters and incorporating the electron spin and broadening of Landau levels, respectively. It is found, taking n‐Hg1−xCdxTe as an example, that the Einstein relation exhibits an oscillatory magnetic field dependence due to Shubnikov–de Haas effect and decreases with increasing alloy composition. Besides the same ratio increases with increasing electron concentration and is in close agreement with the suggested experimental method of determining the Einstein relation in degenerate semiconductors having arbitrary dispersion laws. In addition, the corresponding well‐known results of parabolic semiconductors both in the presence and absence of magnetic field have been obtained from the generalized expressions under certain limiting conditions.

On the diffusivity‐mobility ratio in small‐gap semiconductors in the presence of a strong magnetic field: Theory and suggestion for experimental determination

On the Einstein relation in narrow-gap semiconductors in the presence of a quantizing magnetic field

La masse effective des electrons dans les semi-conducteurs, etant liee a la mobilite des porteurs, est un des parametres importants des dispositifs semi-conducteurs. Parmi les diverses definitions de la masse effective, la masse de la quantite de mouvement effective devrait etre la quantite de base

B. Mitra

Papers

On the effective electron mass in strained layer superlattices of non-parabolic semiconductors under strong magnetic quantization

On the Einstein relation in narrow-gap semiconductors in the presence of a quantizing magnetic field

On the effective electron mass in N-channel inversion layers of Ge

On the thermoelectric power in 3D quantum well structures of small-gap semiconductors in the presence of crossed strong magnetic and electric fields

A simplified analysis of the field emission from semiconductor superlattices under magnetic quantization