Quasi-Two-Dimensional Se-Terminated Bismuth Oxychalcogenide (Bi₂O₂Se)

Abstract

Since the discovery of graphene, van der Waals (vdW) two-dimensional (2D) materials have attracted considerable attention for various potential applications. Recently, a Se-terminated bismuth oxychalcogenide, Bi2O2Se, has been fabricated using the vapor deposition method. Bi2O2Se is not a vdW 2D material, but the as-grown substance shows 2D characteristics. For example, Bi2O2Se exhibits layer number-dependent absorption spectra in experiments, but until now, there has been no reasonable explanation as to why. Here, we propose a 50% Se-passivation surface model, which elucidates the production of such spectra. Our model is also consistent with recent observations using scanning tunneling microscopy. Moreover, high-resolution transmission electron microcopy observations show a broken zipper-like structure in Bi2O2Se. We ascribe Bi2O2Se as a zipper 2D material, and we summarize the characteristics of zipper 2D materials while proposing the development of others. Zipper 2D materials not only are an important subset of 2D materials but also bridge the gap between vdW 2D materials and traditional 3D materials. Because they are a big family, including insulators, semiconductors, and magnetic metals, zipper 2D materials lend themselves to a plethora of applications.

Progress Report on Property, Preparation, and Application of Bi2O2Se

“…As we have mentioned previously, the band structure, thermal transport, and optical absorption of Bi 2 O 2 Se all display a typical feature of layer-dependence, [10,21,29] so it would be feasible to tune these properties through modulation of thickness. Defects in Bi 2 O 2 Se can be induced by synthetic control, such as changing the ratios of raw materials, [36] and shear exfoliation.…”

“…Chen et al verified this way of cleavage through scanning tunneling spectroscopy analysis, [ 11 ] and they observed interlinked weave pattern of Se vacancies and steps’ morphology with edge height of 0.61 nm on Bi 2 O 2 Se surface (as shown in Figure 1c,d). Cheng et al proposed a zipper model for Bi 2 O 2 Se‐like layered materials (Figure 1e), [ 21 ] and it was believed that there is no clear gap between the layers for this type of materials (like Bi 2 O 2 Se in Figure 1b). These materials have stronger interlayer force than most vdW layered materials, although it will cause difficulty in exfoliating bulk Bi 2 O 2 Se into few‐layer structures.…”

“…[ 24a ] It's worth noting that the bandgap of Bi 2 O 2 Se would decrease as the thickness increases, which is similar to that of BP. [ 25 ] But what's different is that the bandgap decreasing from monolayer to bilayer for Bi 2 O 2 Se is much larger than that from bilayer to more layers (as shown in Figure a), [ 21,24b ] and this dramatic drop in bandgap could be due to the cleavage of the [Se] n 2 n − layer in a bilayer structure. While for bulk samples, the cleavage of the [Se] n 2 n − layer would also result in a high concentration of Se deficiencies on the surface.…”

Self‐Driven WSe2/Bi2O2Se Van der Waals Heterostructure Photodetectors with High Light On/Off Ratio and Fast Response

“…has gained wide interest due to its excellent electron mobility and good ambient stability. [ 16,17 ] Tremendous progress has been achieved in the structural analysis, [ 17–19 ] controlled synthesis, [ 20–23 ] precision etching, [ 24 ] noncorrosive transfer, [ 23,25 ] and large area growth [ 26,27 ] of 2D Bi 2 O 2 Se, which paved the way for advanced electronics and optoelectronics device applications. [ 28–31 ] The 2D Bi 2 O 2 Se exhibits an ultra‐high mobility (≈20 000 cm 2 V −1 s −1 ) comparable to graphene and proper band gap of 0.8 eV, it is thus worth exploring its merits in high‐performance photodetection applications.…”

Native O and Se Vacancy Defects in Bi2O5Se, Bi2O9Se3, and Bi2O10Se3 Dielectrics for Nanoelectronics

“…The unique properties of Bi 2 O 2 Se have also been recognized in other application domains, [ 36 ] such as neuromorphic computing, [ 37 ] optoelectronics, [ 38–42 ] ferroelectronics, [ 43,44 ] magnetoelectronics, [ 45 ] and thermoelectrics. [ 46–48 ] Recent investigations on the fundamental properties of Bi 2 O 2 Se, including defects, [ 49–51 ] band structures, [ 52,53 ] and so on, have gained more insights into this material for its developmental applications.…”