(Invited) Wafer-Scale Integration of 2D TMD Heterostructures of Controlled Layer Orientation on Arbitrary Substrates Towards Mechanically-Reconfigurable Electronic Devices

Abstract

Advancements of modern electronics have demanded to incorporate a diverse set of additional functionalities into device platforms such as high mechanical deformability and improved material/process sustainability. Traditional silicon (Si) wafers-based device manufacturing is intrinsically limited in realizing such novel aspects owing to their rigid/bulky nature as well as complex and unsustainable process schemes. Two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors are highly promising owing to their extremely large mechanical flexibility and near atom thickness coupled with van der Waals (vdW) attraction-enabled relaxed assembly requirement. Major challenges for realizing such opportunities for emerging electronics have been associated with a lack of reliable manufacturing methods to precisely separate 2D TMD layers from original growth wafers and integrate them on desired functional substrates in a controllable, scalable, and sustainable manner. In this talk, I will discuss recent efforts in my group on exploring viable manufacturing strategies to assemble wafer-scale 2D TMD layers of heterogeneously tailored components on arbitrary substrates. We grew various 2D TMD layers of controlled layer orientation on specially-treated growth substrates with high hydrophilicity or water solubility via a chemical vapor deposition (CVD) process. By taking advantage of the large surface energy contrast between growth substrates vs. grown 2D TMDs, we precisely peel off wafer-scale 2D TMD layers from their original substrates using water preserving their intrinsic structural/chemical integrity. We then integrate them on substrates of virtually unrestricted kinds and shapes in a layer-by-layer fashion, realizing heterogeneously-assembled wafer-scale 2D TMDs layers on a variety of exotic substrates impossible with any conventional approaches. The achieved material quality has been characterized via extensive microscopy/spectroscopy techniques, and the original substrates have been sustainably recycled for sequential growth and integration. Several demonstrations of 2D TMDs-enabled mechanically reconfigurable electronic devices will be presented, which will be impossible with any other traditional materials. This novel manufacturing strategy is believed to greatly broaden the applicability of 2D TMDs in emerging areas of electronics such as three-dimensionally conformal electronic devices of unconventional forms factors.