Layer-resolved release of epitaxial layers in III-V heterostructure via a buffer-free mechanical separation technique

Abstract

Layer-release techniques for producing freestanding III-V epitaxial layers have been actively developed for heterointegration of single-crystalline compound semiconductors with Si platforms. However, for the release of target epitaxial layers from III-V heterostructures, it is required to embed a mechanically or chemically weak sacrificial buffer beneath the target layers. This requirement severely limits the scope of processable materials and their epi-structures and makes the growth and layer-release process complicated. Here, we report that epitaxial layers in commonly used III-V heterostructures can be precisely released with an atomic-scale surface flatness via a buffer-free separation technique. This result shows that heteroepitaxial interfaces of a normal lattice-matched III-V heterostructure can be mechanically separated without a sacrificial buffer and the target interface for separation can be selectively determined by adjusting process conditions. This technique of selective release of epitaxial layers in III-V heterostructures will provide high fabrication flexibility in compound semiconductor technology.

Analysis of Crystalline Defects Caused by Growth on Partially Planarized Spalled (100) GaAs Substrates

“…The spalling fracture for (100)-oriented GaAs substrates produces a regularly corrugated surface of >5 µm peak-to-trough height facets [21,22]. Recent advances in spalling techniques have enabled predominantly smooth surfaces; however, faceted regions can still remain and are largely unavoidable without fracture-guiding layers due to the orientation of favorable fracture planes [23,24]. Ideally, the fracture surfaces can be grown on directly without the added cost related to external planarization, e.g., chemomechanical polishing.…”

Controlling the Balance between Remote, Pinhole, and van der Waals Epitaxy of Heusler Films on Graphene/Sapphire

“…These examples illustrate that epitaxy to the substrate and exfoliation are insufficient to prove a remote mechanism . Moreover, graphene is not always required for exfoliation: interfacial strains in thin film heterostructures can also enable exfoliation without the need for a graphene interlayer . New forms of evidence are needed to experimentally validate a remote epitaxy mechanism.…”