High-Efficiency GaAs Solar Cells Grown on Porous Germanium Substrate with PEELER Technology

III-V solar cells are mainly grown on GaAs or Ge substrate, which significantly contributes to the final cost and affects the sustainable use of these rare materials. A so-called PEELER process is developed, in which a porosification technique is used to create a weak layer between a Ge substrate and the epitaxial layers. This method enables the separation of the grown layers, allowing for the subsequent reuse of germanium and a reduction in the environmental and economic cost of optoelectronic devices. Technology validation using the device performance is important to assess the technology interest. For this purpose, the performance of 22 nondetached single-junction GaAs photovoltaic cells grown and manufactured on porosified 100 mm Ge wafer without antireflection coating is fabricated and compared. All the cells exhibit comparable performance to state-of-the-art GaAs solar cells (grown or Ge or GaAs) with high efficiency (21.8% +/- 0.78%) and thereby demonstrate the viability of growing high-performance optoelectronic devices on detachable Ge films. Herein, monocrystalline GaAs/Ge epitaxial layers are grown on 100 mm (4") porosified germanium wafers using metal organic chemical vapor deposition. The single-junction photovoltaic cells, fabricated through front-side processing on these structures, demonstrate efficiencies of up to 23.1%. This work paves the way for detachable III-V solar devices and reusable germanium wafers.image (c) 2023 WILEY-VCH GmbH