Multi-shell spherical GaAs/AlxGa1−xAs quantum dot shells-size distribution as a mechanism to generate intermediate band energy levels

In this work the generation of an intermediate band of energy levels from multi-shell spherical GaAs/AlxGa1−xAs quantum dot shells-size distribution is reported. Within the effective mass approximation the electronic structure of a GaAs spherical quantum-dot surrounded by one, two and three shells is studied in detail using a numerically stable transfer matrix method. We found that a shells-size distribution characterized by continuously wider GaAs domains is a suitable mechanism to generate the intermediate band whose width is also dependent on the Aluminium concentration x. Our results suggest that this effective mechanism can be used for the design of wider intermediate band than reported in other quantum systems with possible solar cells enhanced performance.