Researchers Demonstrate Innovative Method to Fabricate Wire Arrays
Researchers at the NSF-funded Engineering Research Center (ERC) for Quantum Energy and Sustainable Solar Technologies (QESST), which is headquartered at Arizona State University, have demonstrated an innovative method for fabrication of arrays of both indium phosphide (InP) and silicon (Si) wires. Using this method, wires are defined by etching high-aspect-ratio structures in single crystal InP and Si wafers; the wire arrays are subsequently embedded in a polymer film and removed from their substrates by a mechanical peeling process.
This epitaxy-free, etch-peel fabrication approach enables synthesis, for both III-V materials (non-Si semiconductor compounds) and Si, of multiple and highly flexible solar-cell absorber layers from a single wafer. This innovation has potential to dramatically lower the fabrication costs of both III-V and Si photovoltaic (PV) absorber layers in future III-V/Si tandem solar cells.
A challenge in future low-cost, tandem solar-cell manufacturing is to simultaneously reduce the cell cost and increase the cell efficiency. Peeled wire arrays enable the synthesis of single crystal PV-active-layer building blocks for tandem cells without epitaxy or consumption of an entire wafer.
Results to date indicate opto-electronically active InP wire arrays can be achieved with simple non-vacuum processing methods. For Si wires, microsecond minority carrier lifetimes are measured after peel off.
InP nanowires exhibit efficient light absorption, even in sparse arrays. This process does not require epitaxial growth and also enables synthesis of many III-V solar-cell absorber layers per InP wafer.