Specific Growth and Characterization Issues in Multi-Junction Solar Cells for Concentrations Above 1000 Suns

This work presents some lines of research currently being investigated in our group that are aimed to contribute to a better performance of multi-junction solar cells at very high concentrations (~1000 suns) and, in addition, to achieve a better characterization of these devices also at high concentrations. The improvement of the performance of the solar cell at high concentrations is addressed in two ways. First, a set of results is presented to ascertain the potential of tellurium as a possible n-type dopant to improve the performance of tunnel junctions. Then, the contribution of the bottom cell BSF layer to the series resistance is analysed. On the other hand, the issue of the linearity of the short circuit current with the irradiance is investigated. This linearity is assessed by measuring the external quantum efficiency of solar cells with bias lights of different intensities