Confined electron and shallow donor states in graded GaAs/AlxGa1-xAs spherical quantum dots
Departamento de Física, Universidade Federal do Ceará,
C.P. 6030, Campus do Pici, 60455-760 Fortaleza, Ceará, Brazil
Published online: 15 March 2000
A theoretical study is performed on the confined electron and shallow donor states properties in graded GaAs/AlxGa1-xAs spherical quantum dots. The two lowest energy levels of a confined electron are obtained taking into account the dependence of the electron effective mass on the spatial profile of the Al molar fraction. The ground state of a single Si shallow donor, which may be located at an arbitrary position in the structure, is calculated through a variational approach. Depending on the dot interface width and localization, we find that the energy levels of the electron and donor states for the system under study can be blue or red shifted appreciably in comparison to those calculated within the sharp interface picture. We show that it is necessary to have accurate information concerning the interface of semiconductor dots whose samples are used in the experiments, in order to achieve a better understanding of their optical properties.
PACS: 68.10.Gw – Interface activity, spreading / 68.65.+g – Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties / 71.23.An – Theories and models; localized states
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000