Controlled Spalling of (100)-Oriented GaAs with a Nanoimprint Lithography Interlayer for Thin-Film Layer Transfer Without Facet Formation

Controlled spalling is a potentially low-cost, facile layer transfer technique that can be used for a variety of thin-film device applications and can enable reuse of expensive, single-crystal wafer substrates. However, controlled spalling of (100)-oriented GaAs substrates, commonly used in III-V device growth, suffers from the need for fracture surface repreparation before the wafer can be reused due to the formation of large triangular facets. In this work, we demonstrate facet suppression in (100)-GaAs through the use of buried nanoimprint lithography (NIL) patterned layers that guide the spalling fracture along more favorable paths than the facet-forming path. We show the fracture interaction with three NIL patterned interlayers that have varying aspect ratio, arrangement, and feature shapes and demonstrate the constraint of the fracture path to within <200 nm in height compared to the 5–10 µm facet height observed with controlled spalling of (100) GaAs without a buried interlayer. Our observations show that patterns with high fill factor and continuity in the spall direction as well as the presence of voids in the overgrowth above the features are all beneficial to facet suppression during controlled spalling of thin films from (100) GaAs substrates. Our results can be used in conjunction with overgrowth optimization to further improve this technique for low-cost layer transfer and wafer reuse with (100)-oriented GaAs substrates.