Epitaxial Growth of 2D Ultrathin Metastable γ‐Bi₂O₃ Flakes for High Performance Ultraviolet Photodetection

Abstract

Although UV photodetectors based on a few kinds of 2D wide bandgap semiconductors have been investigated, their low detection capability still hinders the practical application. [18][19] For example, wide bandgap h-BN has been developed for UV detection, but exhibits a poor performance with responsivity of 0.1 mA W −1 and detectivity of 2.4 × 10 8 Jones. [19] Therefore, it is urgent to develop 2D materials with suitable bandgap, excellent light-matter interaction and high stability for high-performance UV detection.Bi 2 O 3 is a semiconductor with many intriguing properties, such as wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance, exhibiting great potential for UV detection. [16][17][18][19][20] There are four main crystal phases for Bi 2 O 3 , including monoclinic (α), [20][21] tetragonal (β), [22] body-centered cubic (γ), [23] and face cubic (δ). [24] Among them, γ-Bi 2 O 3 is a metastable semiconductor at high temperature and has been proved to exhibit excellent performance in the fields such as photocatalysis and photoelectrochemistry. [25][26] More importantly, γ-Bi 2 O 3 possesses a relatively wide bandgap of 2.9 eV and high absorption in the UV region compared with other three phases, [23,[27][28] and thus enabling it great potential for UV detection. Currently, mostly reported γ-Bi 2 O 3 structures are synthesized via liquid-based methods which inevitably introduce various organic impurities, and meanwhile, the size is usually limited to several nanometers, hindering their large-scale application in photoelectronic devices. [23,25,27] With regards to other methods, for instance, annealing of α-Bi 2 O 3 film or thermal oxidization of Bi nanoparticles, could also obtain γ-Bi 2 O 3 structure in nanoscale. [29][30] However, the obtained samples are usually polycrystalline, of which the grain boundaries will affect its intrinsic photoelectrical performance. To the best of our knowledge, it is still challenging to obtain ultrathin 2D γ-Bi 2 O 3 flakes with high quality to meet the requirements of ideal photoelectronic devices.Chemical vapor deposition (CVD) method has been widely used for the growth of ultrathin 2D flakes with high quality and accurately controlled morphology and size of the materials. However, it is still difficult to synthesize 2D γ-Bi 2 O 3 flakes through conventional CVD methods owing to the intrinsic isotropic chemical bonds in the nonlayered γ-Bi 2 O 3 crystal structure. Besides, the mixed phase and metastable nature of γ-Bi 2 O 3 Ultraviolet detection is of great significance due to its wide applications in the missile tracking, flame detecting, pollution monitoring, and so on. The nonlayered semiconductor γ-Bi 2 O 3 is a promising candidate toward highperformance UV detection due to the wide bandgap, excellent light sensitivity, environmental stability, nontoxic and elemental abundance properties. However, controllable preparation of ultrathin 2D γ-Bi 2 O 3 flakes remains a challenge, owing to its nonlayered structure, metastable natu...

2D Oxides for Electronics and Optoelectronics

“…oxides. [15,28,33,34,117,118] Guo et al used MoO 3 mixed with a small amount of NaCl as precursor, reacting with S powder at high temperatures. 2D MoS 2 , MoO 3 -MoS 2 heterojunction, and MoO 3 nanosheets can be obtained when the powder is in different zones, respectively.…”

2D Ultrawide Bandgap Semiconductors: Odyssey and Challenges

“…The relatively wide optical bandgap of the monolayer GaPS 4 nanosheet (4.5 eV) Experimentally obtained optical bandgap of 2D ultrawide bandgap materials. NiPS 3 , [91] BiOCl, [61] GeSe 2 , [99] γ-CuBr, [31] GaSe, [59] GeS 2 , [98] GaS, [32] γ-Bi 2 O 3 , [67] γ-Ga 2 S 3 , [88] GaN, [74] KNb 3 O 8 , [107] β-TeO 2 , [66] Ca 2 Nb 3 O 10 , [35] Sr 2 Nb 3 O 10 , [33] BiOBr, [34] GaPS 4 , [36] α-Sb 2 O 3 , [69] β-Ga 2 O 3 , [108] h-BN, [109] and BeO. [110] endows it great benefit for fabricating solar-blind photodetector (λ < 280 nm).…”

“…[ 58,59 ] Then, the study quickly expand to other chalcogenide and has further inspired attention on other compounds, such as metal oxyhalides, metal nitrides, metal oxides, and Dion–Jacobson perovskite oxides. [ 28,33–35,60–74 ] Atomically thin 2D UWBG semiconductor materials have sky‐rocketing developed into a unique subdiscipline in the last decade, offering new possibilities for designing and fabricating (opto)electronic devices with novel functionalities at the nanoscale ( Figure ). Up to date, studies on 2D UWBG semiconductors have covered the crystal structures, synthesis methods, properties, and device applications.…”

“…[58,59] Then, the study quickly expand to other chalcogenide and has further inspired attention on other compounds, such as metal oxyhalides, metal nitrides, metal oxides, and Dion-Jacobson perovskite oxides. [28,[33][34][35][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74] Atomically thin 2D UWBG semiconductor materials have sky-rocketing developed into a unique subdiscipline in the last decade, offering new possibilities for designing and fabricating (opto)electronic devices with novel functionalities at the nanoscale (Figure 1). Up to date, studies on 2D 2D ultrawide bandgap (UWBG) semiconductors have aroused increasing interest in the field of high-power transparent electronic devices, deep-ultraviolet photodetectors, flexible electronic skins, and energy-efficient displays, owing to their intriguing physical properties.…”

Progress on two-dimensional binary oxide materials

“…The responsivity, detectability, and external quantum efficiency of the photodetector are 3.3 A W −1 and 4.0 × 10 12 Jones and 1600%, respectively, indicating that 2D Ga 2 O 3 has great application potential in solar-blind detectors. Very recently, Wu et al 210 used an epitaxial growth technique to successfully synthesize ultrathin 2D γ-Bi 2 O 3 flakes, and the photodetector had a very good UV detection capability and an ultrafast response speed at 365 nm. Yalagala et al prepared 2D V 2 O 5 that can absorb light from the ultraviolet to the visible range.…”