nxGa1-xN layers, nanowires, and nanodots on Silicon for clean energy applications

Résumé

During this work the constituent functional blocks of a InGaN/Si-based solar-assisted water splitting cell were obtained by molecular beam epitaxy, which includes: • Compact and chemically homogeneous InGaN layers were grown directly on Si substrates over the entire composition range. Such InGaN layers with the InN mole fraction above 30% grown directly on Si are demonstrated for the first time. • InN quantum dots were grown on Si(111), Si(001) and InGaN(0001)/Si(111) substrates by near room temperature droplet epitaxy method. • Selective area grown GaN nanowires with well controlled geometry and structural/optical quality were fabricated by selective area growth method on different quality templates. A dislocation filtering effect was studied in detail. All grown samples were extensively characterized by large variety of tools to confirm their high quality. The photoelectrochemical performance of InGaN-on-Si layers was evaluated and ways to enhance it were proposed, such as improving its stability via NiO protection layers and boosting their performance by InN quantum dots decoration. Overall, despite many challenges, it was demonstrated that InGaN is a very promising material for realization of tandem (with Si cells) water splitting cells.