Self‐Rolling‐Up Enabled Ultrahigh‐Density Information Storage in Freestanding Single‐Crystalline Ferroic Oxide Films

Abstract

Ferroelectric memory is one of the most attractive emerging nonvolatile memory. Conventional methods to increase storage density in ferroelectrics include reducing the storage bit size or fabricating 3D stacks. However, the former will face a physical limit finally, and the integration of single‐crystalline ferroelectric oxide following the latter still remains a great challenge. Here, a new method is introduced to construct a scroll‐like 3D memory structure by self‐rolling‐up single‐crystalline ferroelectric oxides. PbZr0.3Ti0.7O3 single‐crystalline thin film is chosen as a prototype and epitaxially grown on another oxide stressor layer with a few lattice‐mismatch. Releasing such “Pb(Zr, Ti)O3/stressor” bilayered structure from the substrate induces self‐rolling‐up due to the internal stress from the lattice‐mismatch. High‐density information can be written in the form of switched ferroelectric domains on those flat “Pb(Zr, Ti)O3/stressor” membranes via piezoelectric force microscopy. In self‐rolling‐up membranes, information density can be experimentally enhanced up to 45 times. Theoretically, the freestanding “Pb(Zr, Ti)O3/stressor” membranes have a strongly driven force to self‐rolling‐up, and the area ratio can enhance 100–450 times, corresponding to an ultra‐high density information storage of 102 Tbit In−2. This study provides a new and general method to develop compact, high‐density, and 3D memories from oxide materials.

Self‐Rolled‐Up Ultrathin Single‐Crystalline Silicon Nanomembranes for On‐Chip Tubular Polarization Photodetectors

“…Lattice mismatch of Si and Ge results in tensile strain on the single-crystalline Si nanomembrane at the epitaxial interface, and correspondingly, introduces compressive strain on Ge at the epitaxial interface. We calculated strain maps of 𝜖 xx , which range from −5% to +5% by using geometrical phase analysis at atomic scale, [11,12] as shown in Figure 1b and Figure S2b, Supporting Information.…”

“…Freestanding semiconductor nanomembranes with high crystallinity exhibit excellent photonic and optoelectronic single-crystalline nanomembranes can then be assembled to fabricate 3D electronic devices with targeted functions such as highperformance lasers, [23] memories, [11] and photodetectors. [1] Rolled-up nanomembranes, [6,8,24] as a fast-evolving technology, can be combined with existing chip manufacturing methods to convert specified 2D precursor structures into micro/nano tubular devices with 3D geometries, [7,10] which can offer a promising chip integration platform by forming 3D volumetric devices with a more compact aerial footprint.…”

“…[ 6,7 ] 3D self‐assembled freestanding nanomembranes offer a wider range of optical functions and mechanical structural designs than 2D planar materials. [ 8–10 ] Typically, the fabrication process of freestanding 3D single‐crystalline nanomembranes relies on heterogeneous epitaxial techniques with lattice interfaces and artificial termination first, [ 11–14 ] which is often considered as lattice matching. During epitaxial processes, residual strain will be inevitably introduced into epitaxial single‐crystalline nanomembranes via lattice mismatch, which often results in a short lifetime and poor uniformity of planar devices.…”

Freestanding Perovskite Oxide Membranes: A New Playground for Novel Ferroic Properties and Applications

“…e) Optical image of the self‐rolling‐up process. Reproduced with permission [ 75 ] Copyright 2023, Wiley‐VCH. f) H–M curves of the LSMO/BTO heterostructure, where the red line is the in‐plane and out‐of‐plane hysteresis loop in situ, and the blue line is the in‐plane and out‐of‐plane hysteresis loop freestanding.…”

“…Guo et al epitaxially grown NiFe 2 O 4 /PbZr 0.3 Ti 0.7 O 3 /Sr 3 Al 2 O 6 heterostructures on [001]-orient STO substrates. [75] The lattice mismatch in different layers was utilized to load the compressive stress on the NiFe 2 O 4 ferromagnetic layer from the Sr 3 Al 2 O 6 layer and to load tensile stress on the PbZr 0.3 Ti 0.7 O 3 ferroelectric layer from the NiFe 2 O 4 layer. In the lift-off process, the freestanding NiFe 2 O 4 /PbZr 0.3 Ti 0.7 O 3 heterostructure will build a scroll-like 3D memory structure by self-rolling-up (Figure 9e).…”