Freestanding epitaxial SrTiO ₃ nanomembranes via remote epitaxy using hybrid molecular beam epitaxy

Abstract

The epitaxial growth of functional oxides using a substrate with a graphene layer is a highly desirable method for improving structural quality and obtaining freestanding epitaxial nanomembranes for scientific study, applications, and economical reuse of substrates. However, the aggressive oxidizing conditions typically used in growing epitaxial oxides can damage graphene. Here, we demonstrate the successful use of hybrid molecular beam epitaxy for SrTiO 3 growth that does not require an independent oxygen source, thus avoiding graphene damage. This approach produces epitaxial films with self-regulating cation stoichiometry. Furthermore, the film (46-nm-thick SrTiO 3 ) can be exfoliated and transferred to foreign substrates. These results open the door to future studies of previously unattainable freestanding oxide nanomembranes grown in an adsorption-controlled manner by hybrid molecular beam epitaxy. This approach has potentially important implications for the commercial application of perovskite oxides in flexible electronics and as a dielectric in van der Waals thin-film electronics.

Understanding the 2D-material and substrate interaction during epitaxial growth towards successful remote epitaxy: a review

“…Regarding GaN on graphene/GaN, it can be realized using MBE system that requires a low growth temperature of approximately 700 ºC, which temperature enables to avoid the decomposition of GaN substrate, if N-plasma is appropriately controlled [ 234 ]. Recent studies on modified hybrid MBEs [ 235 ] specifically designed for remote epitaxy show that engineering novel growth tools and techniques may be the best route to successful adoption of remote epitaxy on the industrial scale.…”

Remote epitaxial interaction through graphene

“…Moreover, as a 2D material is a layered van der Waals (vdW) material free of dangling bonds, its weak bonding enables remote-epitaxial films to be detached at the 2D layer interface by simple mechanical exfoliation with atomic precision (3). With the increasing demand of freestanding membranes for both research and industry, the remote epitaxy community has rapidly grown over the past few years (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Various families of materials including III-V (1,(4)(5)(6)(7), III-N (2,(8)(9)(10)(11), and complex oxide (12)(13)(14)(15)(16) thin films have been grown and detached from the substrate, and these films have served as fundamental building blocks for stateof-the-art devices by overcoming the limitations of conventional epitaxy (1).…”

On the Role of the Sr3−xCaxAl2O6 Sacrificial Layer Composition in Epitaxial La0.7Sr0.3MnO3 Membranes

“…Nonetheless, in the last few years this field has experienced a major turn boosted by the development of synthetic approaches to detach these epitaxial oxides from the growth substrate and freely manipulate them. [13][14][15] In fact, the fabrication of new artificial heterostructures by assembling very dissimilar materials, their integration in conventional materials such as silicon, plastics, and 2D semiconductors, [16][17][18] and the possibility to obtain spontaneous shaped structures [19] is becoming a reality opening the possibility to study novel interface phenomena, nanoengineer their properties, and unlock strain states that might not be available by traditional epitaxial growth. [20][21][22] The use of a sacrificial layer is an appealing approach to fabricate and manipulate freestanding epitaxial complex oxides membranes.…”