Controlled Synthesis of High-Mobility Atomically Thin Bismuth Oxyselenide Crystals

Abstract

Non-neutral layered crystals, another group of two-dimensional (2D) materials that lack a well-defined van der Waals (vdWs) gap, are those that form strong chemical bonds in-plane but display weak out-of-plane electrostatic interactions, exhibiting intriguing properties for the bulk counterpart. However, investigation of the properties of their atomically thin counterpart are very rare presumably due to the absence of efficient ways to achieve large-area high-quality 2D crystals. Here, high-mobility atomically thin BiOSe, a typical non-neutral layered crystal without a standard vdWs gap, was synthesized via a facial chemical vapor deposition (CVD) method, showing excellent controllability for thickness, domain size, nucleation site, and crystal-phase evolution. Atomically thin, large single crystals of BiOSe with lateral size up to ∼200 μm and thickness down to a bilayer were obtained. Moreover, optical and electrical properties of the CVD-grown 2D BiOSe crystals were investigated, displaying a size-tunable band gap upon thinning and an ultrahigh Hall mobility of >20000 cm V s at 2 K. Our results on the high-mobility 2D BiOSe semiconductor may activate the synthesis and related fundamental research of other non-neutral 2D materials.

Molecular Beam Epitaxy and Electronic Structure of Atomically Thin Oxyselenide Films

“…Mater. [15] In conclusion, we have demonstrated the MBE-growth of atomically thin Bi 2 O 2 Se films down to monolayer by co-evaporating Bi and Se precursors in oxygen atmosphere. We note that the overall observed bands shift upward about 40 meV in the bulk crystal, indicating the slight electron-doping in the as-grown thin film.…”

“…Oxychalcogenides, which can be regarded as mixing and bridging chalcogenides and oxides together, reactivate their research booms for the remarkable phenomena such as high carrier mobility, [9] thermoelectricity, [10][11][12] ferroelectricity, [13] and superconductivity. [2,9,13,[15][16][17][18][19][20][21][22][23] For example, the bulk Bi 2 O 2 Se crystals show an ultrahigh Hall mobility of ≈280 000 cm 2 V −1 s −1 at low temperature [9] and robust bandgap (immune to Se vacancies) after cleavage. [2,9,13,[15][16][17][18][19][20][21][22][23] For example, the bulk Bi 2 O 2 Se crystals show an ultrahigh Hall mobility of ≈280 000 cm 2 V −1 s −1 at low temperature [9] and robust bandgap (immune to Se vacancies) after cleavage.…”

“…[14] Bi 2 O 2 Se, a representative of oxychalcogenides family, emerged as an air-stable highmobility layered semiconductor, which holds promise for next-generation digital devices and optoelectronics. [17] Nanoplates and thin films of Bi 2 O 2 Se were successfully prepared by chemical vapor deposition (CVD), [9,15,21,23] displaying excellent switching behavior of I on /I off and high Hall mobility (up to 450 cm 2 V −1 s −1 ) at room temperature. [17] Nanoplates and thin films of Bi 2 O 2 Se were successfully prepared by chemical vapor deposition (CVD), [9,15,21,23] displaying excellent switching behavior of I on /I off and high Hall mobility (up to 450 cm 2 V −1 s −1 ) at room temperature.…”

2D Metal Chalcogenides for IR Photodetection

“…Very lately, a new star ternary material Bi 2 O 2 Se joins into the 2D family . Bi 2 O 2 Se possesses high Hall mobility (29 000 cm 2 V −1 s −1 at 1.9 K and 450 cm 2 V −1 s −1 at room temperature) and appropriate bandgap of 0.8 eV, which pave the way for high sensitivity and fast response IR photodetection.…”

Strong spin–orbit interaction and magnetotransport in semiconductor Bi2O2Se nanoplates

“…Here, we report on a detailed magnetotransport study of a Bi2O2Se nanoplate field- 19 . Freshly cleaved fluorophlogopite mica is employed as growth substrate, which possesses atomically flat surface and is an ideal substrate to synthesize ultra-thin 2D materials 20,21 .…”