K. Jayakumar

EFFECT OF EMBEDDING NANOPARTICLES ON THERMAL CONDUCTIVITY OF CRYSTALLINE SEMICONDUCTORS: PHONON SCATTERING MECHANISM

We evolve a theoretical model for quantitative analysis of decrease in thermal conductivity (κ) by embedding ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors. The lattice thermal conductivity by incorporating the scattering of phonons with defects, grain boundaries, electrons, and phonons in the model Hamiltonian are evaluated. It is noticed that the ErAs nanoparticles provide an additional scattering mechanism for phonons. The embedding of ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors, the phonon scattering with point defects and grain boundaries become more efficient, which cause in the decrease of thermal conductivity up to half of its value of pure crystal. Conclusively, the temperature dependent of thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers. Numerical analysis of thermal conductivity from the present model shows similar results as those revealed from experiments.

SHAPE EFFECT OF SEMIMAGNETIC QUANTUM DOT ON THE BOUND MAGNETIC POLARON

The effect of geometry, concentration of Mn ion and the magnetic field on the binding energy of a donor and the donor bound magnetic polaronic shift in a finite Cd1–x1Mnx1Te/Cd1–x2Mnx2Te Quantum Dot within the effective mass approximation is carried out employing the variational principle. The results are presented and discussed.

Impurity States and diamagnetic susceptibility of a donor in a triangular quantum well

We have calculated the binding energy and the diamagnetic susceptibility(χdia) of the ground (1s) and few low lying excited states (2s and 2p±) in a GaAs/AlxGa1-xAs Triangular Quantum Well (TQW) for the Al composition of x = 0.3. Since the estimation of gives the carrier localization in nanostructured systems and also the calculation of (χdia) involves the , the same has also been estimated as a function of well width. The Schrodinger equation has been solved using variational technique involving Airy functions in the effective mass approximation. The results are presented and discussed.

An unusual behavior on the electrical properties of various salts of chitosan

The effect of ion sizes of various salts of Chitosan on the electrical properties of solid and liquid polymer electrolyte has been investigated by dissolving Chitosan in various acids like acetic, adipic, formic and succinic acids and for various concentration of acids. An unusual behavior on the electrical properties of the salts of has been observed for solid as compared with the liquid polymer electrolyte. In the liquid polymer electrolyte there is an increase in conductivity with decrease in ion size, which may be due Brownian motion of the ion. Where as in solid polymer electrolyte there is an increase in impedance with decrease in ion size, which may be due to the increase in amorphousity when the size of the salts of Chitosan ion increases.

Effect of ion size of various salts of Chitosan on the electrical properties

The present investigation reports, the influence of ion sizes of various salts of Chitosan on the electrical properties, by dissolving Chitosan in various acids like acetic, adipic, formic and succinic acids and for various concentration. An unusual behavior of ac impedance has been observed which may be due to the increase in amorphousity when the size of the salts of Chitosan ion increases.

EFFECT OF LASER ON THE NONPARABOLICITY OF THE CONDUCTION BAND AND HYDROGENIC IMPURITY STATES IN A SEMICONDUCTOR QUANTUM WELL

The effect of laser on the nonparabolicity of the conduction band for hydrogenic donor states like 1s, 2s, 2p± and 2p0 in a GaAs/AlxGa1-xAs quantum well have been computed in a finite barrier model using variational principle in the effective mass approximation. The limiting values of the ground state and few excited state binding energies for a laser dressed-donor have been obtained. The results are presented and discussed.

Effect of magnetic field on the donor impurity in CdTe/Cd1-xMnxTe quantum well wire

The donor impurity binding energy in CdTe / Cd1-xMnxTe QWW with square well confinement along x – direction and parabolic confinement along y – direction under the influence of externally applied magnetic field has been computed using variational principle in the effective mass approximation. The spin polaronic shift has also been computed. The results are presented and discussed.

The diamagnetic susceptibility of a donor in a semiconductor core shell quantum dot

The effect of Aluminium concentration, shell thickness and size of the core shell Quantum Dot on the Diamagnetic Susceptibility of a donor in the Core Shell Quantum Dot is calculated in the effective mass approximation using the variational method. The results are presented and discussed.

Conductivity studies of Chitosan doped with different ammonium salts: Effect of ion size

In the present investigation influence of ion size on the electrical properties of various ammonium salts of various concentrations doped with Chitosan liquid electrolyte has been studied. The attachment of ammonium salts with Chitosan has been confirmed through FTIR Spectrum. Polarizability is calculated from the refractive index data. Addition of ammonium salts increases the conductivity. It is also observed that increase in ion size, increases the ionic conductivity due to increase in amorphous nature of the material. Increase in concentration leads to increase in conductivity due to the presence of more number of free ions.

Coulomb interaction of acceptors in Cd1−xMnxTe/CdTe quantum dot

The investigation on the effect of confining potential like isotropic harmonic oscillator type potential on the binding and the Coulomb interaction energy of the double acceptors in the presence of magnetic field in a Cd1−xMnxTe/CdTe Spherical Quantum Dot has been made for the Mn ion composition x=0.3 and compared with the results obtained from the square well type potential using variational procedure in the effective mass approximation.