Non‐Destructive Wafer Recycling for Low‐Cost Thin‐Film Flexible Optoelectronics

Compound semiconductors are the basis for many of the highest performance optical and electronic devices in use today. Their widespread commercial application has, however, been limited due to the high cost of substrates. Device costs can be significantly reduced if the substrate is reused in a simple, totally non‐destructive and rapid process. Here, a method that allows the indefinite reuse and recycling of wafers is demonstrated, employing a combination of epitaxial “protection layers”, plasma cleaning techniques that return the wafers to their original, pristine, and epi‐ready condition following epitaxial layer removal, and adhesive‐free bonding to a secondary plastic substrate. The generality of this process is demonstrated by fabricating high performance GaAs‐based photovoltaic cells, light emitting diodes, and metal‐semiconductor field effect transistors that are transferred without loss of performance onto flexible and lightweight plastic substrates, and then the parent wafer is recycled for subsequent growth of additional device layers. This process potentially leads to a transformational change in device cost, arising from the inevitable consumption of the wafer that accompanies conventional epitaxial liftoff followed by chemo‐mechanical polishing.