Freestanding Wide-Bandgap Semiconductors Nanomembrane from 2D to 3D Materials and Their Applications.

Wide-bandgap semiconductors (WBGS) with energy bandgaps larger than 3.4 eV for GaN and 3.2 eV for SiC have gained attention for their superior electrical and thermal properties, which enable high-power, high-frequency, and harsh-environment devices beyond the capabilities of conventional semiconductors. Pushing the potential of WBGS boundaries, current research is redefining the field by broadening the material landscape and pioneering sophisticated synthesis techniques tailored for state-of-the-art device architectures. Efforts include the growth of freestanding nanomembranes, the leveraging of unique interfaces such as van der Waals (vdW) heterostructure, and the integration of 2D with 3D materials. This review covers recent advances in the synthesis and applications of freestanding WBGS nanomembranes, from 2D to 3D materials. Growth techniques for WBGS, such as liquid metal and epitaxial methods with vdW interfaces, are discussed, and the role of layer lift-off processes for producing freestanding nanomembranes is investigated. The review further delves into electronic devices, including field-effect transistors and high-electron-mobility transistors, and optoelectronic devices, such as photodetectors and light-emitting diodes, enabled by freestanding WBGS nanomembranes. Finally, this review explores new avenues for research, highlighting emerging opportunities and addressing key challenges that will shape the future of the field.