Bandgap Optimization of Lattice Matched Triple Junction Solar Cells by Incorporation of InAs Quantum Dots

Intermediate band solar cells using quantum dots (QDs) have been proposed as an approach to increasing solar cell efficiency [1]. This paper presents results of attempts to grow QDs in the GaAs middle cell of lattice matched triple junction solar cells by Metal-Organic Chemical Vapor Deposition (MOCVD). QD size and density as a function of number of layers is studied using atomic force microscopy (AFM). The use of strain compensation for multiple QD layers is presented. Incorporation of QDs into the middle cell of a triple junction device is shown to result in an increased shortcircuit current density with minimal loss in the open circuit voltage. The result is an increase in efficiency of a QD device compared to a baseline device without QDs.