Atomic-Precision Fabrication of Quasi-Full-Space Grain Boundaries in Two-Dimensional Hexagonal Boron Nitride

Abstract

Precise control and in-depth understanding of the interfaces is crucial for the functionality-oriented material design with desired properties. Herein, via modifying the long-standing bicrystal strategy, we proposed a novel nanowelding approach to build up interfaces between two-dimensional (2D) materials with atomic precision. This method enabled us, for the first time, to experimentally achieve the quasi-fullparameter-space grain boundaries (GBs) in 2D hexagonal boron nitride (h-BN). It further helps us unravel the long-term controversy and confusion on the registry of GBs in h-BN, including i) discriminate the relative contribution of the strain and chemical energy on the registry of GBs; ii) identify a new dislocation core-Frank partial dislocation and four new anti-phase boundaries; and iii) confirm the universal GB faceting. Our work provides a new paradigm to the exploiting of structural-property correlation of interfaces in 2D materials.Grain boundaries (GBs), an inevitable structural imperfection in polycrystalline two-dimensional (2D) materials, behave as one-dimensional line defects that connect differently oriented grains of the same material 1,2 . Extensive studies have confirmed that the inherent structures of GBs (e.g., misorientation theoretical predictions, we could derive following rules for GB configurations from our experimental results: i) for |θ|<~38°, both sym-and anti-sym GBs are formed only by 5|7s; ii) for ~38°<|θ|<47°, GBs are comprised of 5|7s and a new type of dislocation core-Frank partial dislocations (5|84|7s or 5|84|...|84|7s) as shown in Figure 4c, d, which was not reported previously. Note that θ>38° sym-GBs can also consist of only 5|7s, as exampled by the GB-(41,5) in Figure S9; iii) for ~47°<|θ|<60°, anti-sym GBs only consists of Frank partial dislocations, while sym-GBs and asym-GBs contain both 5|7s and Frank partial dislocations; and iv) no 4|8 dislocation core was observed (served as ⃑ (1,1) dislocations). Table of contentsSection 1| Out-of-plane warping in the junction between the top and bottom layers 1.1 Out-of-plane warping in the junction with the same orientation (θ=0°) ( Figure S1) 1.2 Out-of-plane warping in the tilted GBs obtained by our experiments (Figure S2) Section 2| Out-of-plane warping in regular planar GBs Section 3| Fabrication of h-BN/graphene hetero-junction (Figure S3) Section 4| Structural evolution of the in situ created holes in 2D h-BN under electron beam irradiation and sample heating (Figure S4 to Figure S5) Section 5| Imaging process (Figure S6) Section 6| Dislocations and line defects in 2D h-BN (Figure S7) Section 7| Details for the full-space GBs (Figure S8 to Figure S11) Section 8| The detailed structure of GBs with 66-BBs (Figure S12) Section 9| The GB energy in 2D h-BN (Figure S13) Section 10| More details about GB faceting 10.1 General description of GB faceting and the associated statistics (Figure S14, 15) 10.2 More details about GB faceting in |θ|<38° GBs (Figure S16 to Figure S18) 10.3 More details about GB faceting in |θ|>38° GBs (F...

Grain rotation and coupled grain boundary motion in two-dimensional binary hexagonal materials

“…This leads to the prevalence of 5|7 dislocation cores in single-component 2D hexagonal materials like graphene [1,3,[10][11][12], with other types of defect motifs being rare. In 2D binary hexagonal materials like h-BN and TMDs the situation is more complex, with a much richer variety of dislocation core structures such as 4|8, 5|7, 4|6, 4|10, 6|8, 4|4, 8|8, and others depending on the specific conditions of grain boundary [4][5][6][7][8][9]. This is related to the distinction between heteroelemental and homoelemental neighborings, and thus the formation of defect core structures containing more energetically favorable A-B heteroele-mental bonds.…”

“…These large-scale samples are often grown by techniques of heteroepitaxy, such as chemical vapor deposition (CVD). While large areas can be covered with atomically thin layers of the desired material via these techniques, the resulting monolayer film is typically polycrystalline, as a result of spontaneous nucleation at various locations on the substrate and the formation and evolution of topological defects including dislocations and grain boundaries as observed in experiments [1,[3][4][5][6][7][8].…”

“…The dynamics of these defects, particularly dislocation glide and climb, result in the motion of grain boundaries, with some grains growing at the expense of others. A large amount of research efforts, both experimentally [1,[3][4][5][6][7][8] and theoretically/computationally [9][10][11][12][13], have been put on the studies of defect dynamics and grain growth as well as the understanding and control of the corresponding mechanisms in various 2D material systems including graphene [1,3,[10][11][12], hexagonal boron nitride (h-BN) [4][5][6]9], and transition metal dichalcogenides (TMDs) [1,7,8].…”

Building Functional Memories and Logic Circuits with 2D Boron Nitride

“…proposed a method to study the effect of strain and chemical energy on the grain boundary registration in h‐BN, distinguishing the relative contribution of these two mentioned factors. [ 114 ] Two kinds of grain boundaries are depicted in Figure 3e, i.e., bisector 5|7 grain boundaries and bisector 4|8 grain boundaries. The bisector 5|7 grain boundaries stayed along with new Frank partial dislocations.…”

“…), and lattice dislocations (Reproduced with permission. [ 114 ] Copyright 2019, American Chemical Society. ), has enlightened the BN resistive switching devices, memory transistors (Reproduced with permission.…”