III-V Hetero-EpitaxiaL Lateral Overgrowth on Si tunnel oxide from nano-seeds array for PhotoVoltaics – HELLO_PV

The HELLO_PV project develops an innovative solution to III-V on silicon heterogeneous material integration, a holy grail with wide societal applications in opto-electronics. More precisely, this proposal aims to develop the materials and technological building blocks to develop an AlGaAs/Si tandem junction cell using cost effective methods and innovative growth mechanisms. This is competitive with other potential approaches, such as the emerging field of perovskites, in ensuring far more stable materials, with very low III-V material requirement and no III-V or Ge substrate required helping maintain low cost and with very low usage of scarce materials. The proposal builds on the achievement of an innovative strategy to integrate directly defect-free micrometric size GaAs crystals monolithically on silicon by epitaxial lateral overgrowth through nanoholes patterned in a very thin SiO2 layer covering the silicon substrate. This technique leads to a very good electrical connection not only between the GaAs crystals and the Si substrate, but also across the GaAs/SiO2/Si sandwich (tunneling assisted transport) which led to state-of-the-art breakthrough. This proposal aims to extend this strategy to Al(0.18)Ga(0.82)As compounds which is the composition required to achieve current matching and an optimum conversion efficiency for an AlGaAs/Si tandem solar cell of 32%.