Investigation of new approaches

The objective of this study is to investigate new approaches that may overcome the issuesof phase separation and high dislocation density in InxGa1¿xN materials with high indiumconcentration, for the realization of high efficiency InxGa1¿xN based solar cells.Two novel approaches are proposed that may overcome the basic challenges involvedin the InxGa1¿xN heterojunction solar cells. The first approach consists in the growthof a thick multi-layered InGaN/GaN absorber, called Semibuk approach. These GaNinterlayers need to be thick enough to be effective and thin enough to allow carrier trans-port through tunneling. The InxGa1¿xN layers need to be thick and numerous enoughto absorb efficiently the incoming light beam, and thin enough to remain fully strainedand without phase separation. The second approach consists in the growth of InxGa1¿xNnano-structures for the achievement of high indium content thick InxGa1¿xN layers. Itallows the elimination of the preexisting dislocations in the underlying template. It alsoallows strain relaxation of InxGa1¿xN layers without any dislocations, leading to higherindium incorporation and reduced piezoelectric effect.