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Copyright of Revista CienciaUAT is the property of Universidad Autonoma de Tamaulipas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Theoretical calculations of the energy and wave function of the ground state and the first excited state of an electron confined in a GaAsAl/GaAs quantum well with Morse-like potential profile are presented using the effective mass approximation method and the envelope wave function. The inter-sub-band transitions according to the parameters defining the geometry of the Morse potential, to represent the inter-diffusion between materials of the barrier and the well, are analyzed. Additionally, are shown the peaks of the nonlinear optical rectification as a function of energy of incident photons and its resonance with the transition energy between the two states. An electric field is applied in the growth direction of the quantum well and a magnetic field perpendicular to the heterostructure in order to study the shifts of the optical response peaks in the spectrum of the incident photons. [ABSTRACT FROM AUTHOR]

Copyright of Superficies y Vacío is the property of Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A theoretical study of the GaAs/GaInNAs solar cells based on a multi-quantum wells (MQWSC) and superlattices (SLSC) configuration is presented for the first time. The conversion efficiency as a function of wells width and depth is modeled. The photon absorption increases with the quantum well levels in- corporation and therefore the photocurrent as well. It is shown that the MQWSC efficiency overcomes the solar cells without quantum wells about 25%. A study of the SLSC viability is also presented. The conditions for resonant tunneling are established by the matrix transfer method for a superlattice with variable quantum wells width. The effective density of states and the absorption coefficients for SL structure are calculated in order to determinate the J-V characteristic. The influence of the superlattice or cluster width in the cell efficiency is researched showing a better performance when width and the number of cluster are increased. The SLSC efficiency is compared with the optimum efficiency obtained for the MQWSC showing that it is reached an amazing in-crement of 27%. [ABSTRACT FROM AUTHOR]

In this work, the binding energy of a hydrogenic impurity in a GaAs/InxGa1-xAs quantum well is calculated as a function of the well width and the impurity position inside the quantum well. The calculations are performed within the effective-mass approximation and using a variational method for different In concentrations (0 < x < 0.4) in GaAs. We have kept in mind that the confinement potential is modified by the strain due to the differences of the lattice constants between GaAs and the InxGa1-xAs, which is included in the confinement potential as suggested by Atanasov. We found that the impurity binding energy is between 8 meV and 10meV, for well widths between 50A and 150A. This range of energy is characteristic of the infrared spectrum. We also found that the impurity binding energy varies with the impurity location in the well region, being greater for on-center and lower for on-edge impurity position. [ABSTRACT FROM AUTHOR]

The use of low dimensional structures is a key technological element in the creation of new quantum functional devices in the development of the next generation of the electronic, photonic, and spintronic integrated circuits and many other nanoscaled devices that are necessary for the information society of 21st century. One of the most important optical properties is the photoluminescence produced by agents as impurities and excitons in GaAs quantum wells, wires, and dots with nanometric dimensions under the influence of electric and magnetic fields and external pressures. The binding energy for the first three excitonic states in GaAs/GaI-x A1xAs quantum wells describing the system through quantum theory in the effective mass approximation and using the variational method is presented. [ABSTRACT FROM AUTHOR]