Ramírez Morales, Alejandro; Martínez Orozco, Juan Carlos; Rodríguez Vargas, Isaac
Resumen:
We study the quantum confined stark effect (QCSE) characteristics in Gaussian quantum wells
(GQW). This special energy band profile is built varying the aluminum concentration of the
AlGaAs ternary alloy in Gaussian fashion. The semi-empirical sp3
s
* tight-binding model including
spin is used to obtain the energy Stark shifts (ESS) and the wave-function Gaussian spatial overlap
(GSO) between electrons and holes for different electric field strengths, quantum well widths and
aluminum concentrations. We find that both the ESS and the GSO depend parabolically with
respect to the electric field strength and the quantum well width. These QCSE characteristics show
an asymmetry for the electric field in the forward and reverse directions, related directly to the
different band-offset of electrons and holes, being the negative electric fields (reverse direction)
more suitable to reach greater ESS. Two important features are presented by this special energy
band profile: (1) reductions of the ESS and (2) enhancements of the GSO of tents to hundreds with
respect to parabolic and rectangular quantum wells. Even more, tailoring the quantum well width it
is possible to reach GSO of thousands with respect to rectangular quantum wells. Finally, it is
important to mention that similar results could be obtained in other quantum well heterostructures
of materials such as nitrides, oxides (ZnO), and SiGe whenever the confinement band profiles are
modulated in Gaussian form