Controlled Synthesis of High-Mobility Atomically Thin Bismuth Oxyselenide Crystals

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Non-neutral layered crystals lack a van der Waals (vdWs) gap, featuring strong in-plane chemical bonds and weak out-of-plane electrostatic interactions.
• Investigating atomically thin non-neutral layered materials is challenging due to difficulties in achieving large-area, high-quality crystals.

Purpose of the Study:

• To develop an efficient method for synthesizing large-area, high-quality atomically thin non-neutral layered crystals.
• To explore the optical and electrical properties of synthesized bismuth oxy-selenide (Bi2O2Se) and assess its potential for future research.

Main Methods:

• Utilized a facile chemical vapor deposition (CVD) method for the synthesis of atomically thin Bi2O2Se.
• Achieved precise control over crystal thickness, domain size, nucleation site, and crystal-phase evolution during synthesis.
• Obtained large single crystals of Bi2O2Se with lateral sizes up to ~200 μm and thicknesses down to the bilayer.

Main Results:

• Successfully synthesized high-quality, atomically thin Bi2O2Se crystals with controllable properties.
• Observed a size-tunable band gap in the 2D Bi2O2Se crystals upon thinning.
• Recorded an ultrahigh Hall mobility exceeding 20,000 cm² V⁻¹ s⁻¹ at 2 K, indicating excellent electrical performance.

Conclusions:

• The developed CVD method provides an efficient route to large-area, high-quality 2D non-neutral layered materials.
• The high-mobility 2D Bi2O2Se semiconductor opens avenues for fundamental research into this class of materials.
• This work may stimulate the synthesis and investigation of other novel non-neutral 2D materials.