Artificially designed heterostructures through freestanding nanomembranes for new physcial coupling and M3D integration

The landscape of electronics, photonics, and optoelectronics has undergone a profound transformation, transitioning from being rigid to being flexible, from single functionality to multifunctionality, and from lateral integration to vertical integration. To embrace this paradigm shift, material innovations have become a requirement. Conventional materials have relied on thick and rigid wafers, but these materials are not ideal for the emerging paradigm due to their inherent property. They exhibit high stiffness, high required adhesion energy, and substantial internal stress, rendering them unsuitable as a building block for this shift. Addressing this challenge, it has been explored to create a new class of material building blocks called "freestanding nanomembranes". They possess an exceptionally low stiffness, rendering them suitable to flexible applications. Moreover, their minimal required adhesion energy enables vertical stacking of multiple freestanding nanomembranes, facilitating the realization of novel heterostructures, called artificial heterostructures, for new physical coupling and multifunctionality. Notably, their remarkably low internal stress positions them as an ideal material building block for vertically integrated devices. As a result, freestanding nanomembranes are expected to play a central role in steering this transformative journey.
In this talk, I would like to share our team’s endeavor on realizing freestanding nanomembranes, physical coupling, and their applications. First of all, we have conceived an approach to obtain various freestanding single crystalline materials through 2D materials-assisted layer transfer (2DLT). While developing it, we found out that crystallographic information can penetrate through graphene as long as substrates have polarity because of graphene’s information transparency. Second, we realized that geometrical confinement facilitates kinetic control of 2D materials, which secures crystallinity, layer-controllability, and heterostructures. Thereby we for the first time succeeded in producing single crystalline 2D materials on amorphous substrate without epitaxial relationship. Lastly, the development of 3D and 2D nanomembranes enables the creation of a new class of heterostructures, artificial heterostructures, exhibiting exciting physical couplings in terms of electronic, optic, and thermal properties. Also, they hold great promise for practical applications such as in-sensor computers, vdW integrated photonics chips, and monolithic 3D (M3D) integrated electronics