Epitaxy of single-crystalline materials laid the foundation for numerous electronics as a core technology. Nevertheless, because the single-crystalline epilayers are covalently bonded to substrates, only limited applications were explored. The recent development of layer transfer techniques has suggested another way involving the production of freestanding membranes that are free from substrates. In this review, we comprehensively catalog recent advances for freestanding-membrane-based electronics from transistors and memory storage to sensors and energy harvesters. We highlight their unique advantages, including flexibility, unique physical coupling, heterointegrability, and costeffectiveness, and summarize their challenges and perspectives.
Epitaxy technology produces high-quality material building blocks that underpin various fields of applications. However, fundamental limitations exist for conventional epitaxy, such as the lattice matching constraints that have greatly narrowed down the choices of available epitaxial material combinations. Recent emerging epitaxy techniques such as remote and van der Waals epitaxy have shown exciting perspectives to overcome these limitations and provide freestanding nanomembranes for massive novel applications. Here, we review the mechanism and fundamentals for van der Waals and remote epitaxy to produce freestanding nanomembranes. Key benefits that are exclusive to these two growth strategies are comprehensively summarized. A number of original applications have also been discussed, highlighting the advantages of these freestanding films-based designs. Finally, we discuss the current limitations with possible solutions and potential future directions towards nanomembranes-based advanced heterogeneous integration.
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