Controlled Cracking For Large-Area Thin Film Exfoliation: Working Principles, Status, And Prospects

The production of flexible monocrystalline semiconductor thin films less than a few tens of micrometers in thickness is currently receiving huge interest in various emerging applications such as mobile health care (mHealth), wearable devices, smart cities, and Internet of things (IoT). However, conventional techniques fail to produce wafer-scale monocrystalline thin films without the use of sophisticated equipment. Recently, the controlled cracking method has shown promise as a facile and scalable method to produce monocrystalline inorganic semiconductor thin films such as Si, Ge, III-V, and III-N materials. In this method, a crystalline semiconductor thin film can be exfoliated from its thick donor substrate via subsurface crack propagation. The cracking based layer transfer approach does not require expensive processing equipment and enables the production of multiple thin films from the same donor substrate. In this review, we present the working principles, recent progress, and future prospects of this emerging crack-assisted layer transfer technology. The unique advantages of this technology for state-of-the-art flexible (opto)electronics are also highlighted. This review offers insights for the fabrication of large- scale flexible monocrystalline semiconductors, which is crucial for the development of next-generation (opto)electronics.