Horizontally Self‐Standing Growth of Bi₂O₂Se Achieving Optimal Optoelectric Properties

Abstract

Air‐stable 2D Bi2O2Se material with high carrier mobility appears as a promising semiconductor platform for future micro/nanoelectronics and optoelectronics. Like most 2D materials, Bi2O2Se 2D nanostructures normally form on atomically flat mica substrates, in which undesirable defects and structural damage from the subsequent transfer process will largely degrade their photoelectronic performance. Here, a new synthesis route involving successive kinetic and thermodynamic processes is proposed to achieve horizontally self‐standing Bi2O2Se nanostructures on SiO2/Si substrates. Fewer defects and avoidance of transfer procedure involving corrosive solvents ensure the integrity of the intrinsic lattice and band structures in Bi2O2Se nanostructures. In contrast to flat structures grown on mica, it displays reduced dark current and improved photoresponse performance (on–off ratio, photoresponsivity, response time, and detectivity). These results indicate a new potential in high‐quality 2D electronic nanostructures with optimal optoelectronic functionality.

2D Bi2O2Te Semiconductor with Single‐Crystal Native Oxide Layer

“…As a member of the bismuth oxychalcogenides family (Bi 2 O 2 X; XS, Se, and Te), Bi 2 O 2 Se displays excellent air stability, high carrier mobility, quantum transport behavior, and good photo electric performance, which has gained much attention recently. [1][2][3][4][5][6][7][8][9][10] However, hindered by the difficulty in synthesis, experimental reports of its analog Bi 2 O 2 Te (electrostatically stacked [Bi 2 O 2 ] n 2n+ and [Te] n 2n− layers) remain rather rare by now, even though theoretical studies have predicted its intriguing characteristics such as good air stability, narrow bandgap (≈0.16 eV), high carrier mobility, and very low thermal conductivity. [3,11,12] It is also inferred that Te atoms in Bi 2 O 2 Te lattice may deviate from the center of Bi cube by ≈5.5 pm, which is distinct from the case of Bi 2 O 2 Se, indicating an inclinable spontaneous polarization characteristic.…”

Integration of Self‐Passivated Topological Electrodes for Advanced 2D Optoelectronic Devices

“…Based on first-principles calculations (Note S4 and Figure S12, Supporting Information), KPFM results and previous researches, [29,[53][54][55] energy band alignments of the Ti/Au-WSe 2 In the dark, the thermal emission of free carriers from these mid-gap states (magenta arrows) results in high dark current (Figure 2b). [56] In addition, these mid-gap states at the interface induce chemical interactions that result in Fermi-level pinning (FLP). [16] For the Bi 2 Se 3 -WSe 2 system, as shown in Figure 3c, the contact interface is electronically sharp and atomically clean, minimizing the dark current sources and depinning the Fermilevel.…”

Promoting 2D Material Photodetectors by Optical Antennas beyond Noble Metals

“…[ 4–8 ] They have manifested a series of advantages including naturally‐passivated surface, thickness/strain/torsion‐regulated bandgap, excellent in‐plane carrier mobility, Si‐complementary metal‐oxide–semiconductor processing compatibility, outstanding flexibility, etc. Thus far, hundreds of 2DLMs have been explored including elemental semiconductors and their derivatives, [ 9–13 ] nitrides, [ 14 ] phosphides, [ 15,16 ] transition metal dichalcogenides, [ 17–28 ] post transition metal chalcogenides, [ 29–35 ] transition metal halides, [ 36–38 ] solid solutions, [ 39 ] multi‐element compounds, [ 40–56 ] topological insulators, [ 57,58 ] alloys, [ 59 ] etc. Their bandgap values range from 0 up to 6 eV, theoretically enabling them to meet the diverse practical applications in various wavebands.…”

“…[4][5][6][7][8] They have manifested a series of advantages including naturally-passivated surface, thickness/strain/torsion-regulated bandgap, excellent in-plane carrier mobility, Si-complementary metal-oxidesemiconductor processing compatibility, outstanding flexibility, etc. Thus far, hundreds of 2DLMs have been explored including elemental semiconductors and their derivatives, [9][10][11][12][13] nitrides, [14] phosphides, [15,16] transition metal dichalcogenides, [17][18][19][20][21][22][23][24][25][26][27][28] post transition metal chalcogenides, [29][30][31][32][33][34][35] transition metal halides, [36][37][38] solid solutions, [39] multi-element compounds, [40][41][42][43][44][45][46][47][48][49][50]…”