Tuning the properties of InAs/GaAs quantum dots through a modified capping layer: Application to optoelectronic devices

Abstract

Quantum-dot (QD) technology has become a very transversal technology finding application in an increasing number of scientific and industrial fields. At the forefront of this development is the well-studied InAs/GaAs QD system. However, the limitations imposed by the fixed InAs-GaAs band offsets and by the difficulties to control the QD morphology due to the capping process still difficult the precise control of QD band structure that would allow the required design in different applications. The use of a certain capping layer (CL) material different than GaAs has been particularly employed to tune the ground state energy of InAs/GaAs QDs through strain and band structure engineering, so achieving the longwavelength telecommunication windows as one of the most pursued targets. This work is mainly focused on the achievement of a higher tunability of the properties of InAs/GaAs QDs by the application of thin GaAs(Sb)(N) CLs and the optimization of the capping process in order to improve their suitability to any optoelectronic device, and more in particular to laser diodes and solar cells. GaAs(Sb)(N)/InAs/GaAs QDs are a highly versatile system in which the use of Sb and N allows for the tunability of the QD ground state while providing a huge degree of freedom regarding the QD-CL band-alignment, according to the requirements of the field of application. quieren, por lo tanto, enfoques alternativos con el fin de mejorar la eficiencia de conversión. En particular, se demuestra que parámetros como la profundidad del pozo de potencial en el CL, su espesor, y su estructura, así como el alineamiento de bandas resultante, juegan un papel importante en la extracción y el transporte de portadores en células solares de QD.