High Mobility Two-Dimensional Bismuth Oxyselenide Single Crystals with Large Grain Size Grown by Reverse-Flow Chemical Vapor Deposition

Abstract

2D semiconductors with atomically thin body thickness have attracted tremendous research interest for high-performance nanoelectronics and optoelectronics. Most of the 2D semiconductors grown by chemical vapor deposition (CVD) methods suffer from rather low carrier mobility, small single-crystal size, and instability under ambient conditions. Here, we develop an improved CVD method with controllable reverse-gas flow to realize the direct growth of quality Bi2O2Se 2D single crystals on a mica substrate. The applied reverse flow significantly suppresses the random nucleation and thus promotes the lateral size of 2D Bi2O2Se crystals up to ∼750 μm. The Bi2O2Se field-effect transistors display high-room-temperature electron mobility up to ∼1400 cm2·V–1·s–1 and a well-defined drain current saturation. The on/off ratio of the Bi2O2Se transistor is larger than 107, and the sub-threshold swing is about 90 mV·dec–1. The responsivity, response time, and detectivity of Bi2O2Se photodetectors approach up to 60 A·W–1, 5 ms, and 2.4 × 1010 Jones at room temperature, respectively. Our results demonstrate large-size and high-quality Bi2O2Se grown by reverse-flow CVD as a high-performance channel material for next-generation transistors and photodetectors.

Salt‐Assisted Low‐Temperature Growth of 2D Bi2O2Se with Controlled Thickness for Electronics

“…The largest currently reported domain sizes of single crystalline Bi 2 O 2 Se are in the range of ≈10–750 µm (Figure 1d). [ 25,28,30,39–41,60–62 ]…”

Hydrogen‐Assisted Synthesis of Large‐Size 2D Bismuth Telluride Flakes for Broadband Photodetection up to 2 µm

“…All these three indexes decrease with increasing incident light power, which is consistent with previous reports. [ 3d,28a,29 ] The optical absorption of Bi 2 Te 3 decreases with increasing wavelength (Figure S16, Supporting Information), which means that the number of photogenerated carriers decreases. Therefore, the photocurrent and responsivity also decay with increasing wavelength.…”

Self-Powered and Broadband Bismuth Oxyselenide/p-Silicon Heterojunction Photodetectors with Low Dark Current and Fast Response

“…The emerging layered bismuth oxyselenide (Bi 2 O 2 Se) nanosheet stimulates a tremendous interest among researchers in academic and industrial areas benefiting from moderate band gap, good air stability, and superior electron mobility. , Researchers have developed different methods for Bi 2 O 2 Se synthesis and proved its photoelectric ability in ultraviolet (UV), visible (vis), and near-infrared (NIR) light. − For instance, Li et al synthesized Bi 2 O 2 Se by a hydrothermal method and investigated its photoresponse properties at 360–785 nm, yet it showed a limited responsivity ( R ) of 75.14 A/W and a detectivity ( D *) of 3.95 × 10 12 cm Hz 1/2 W –1 due to low crystallinity. The chemical vapor deposition (CVD) method is another common fabrication method of 2D materials.…”

“…Wu et al prepared Bi 2 O 2 Se with high crystallinity on mica by taking Bi 2 O 3 and Bi 2 Se 3 as precursors. Khan et al and Yang et al produced 2D Bi 2 O 2 Se single crystals with domain sizes up to several hundred micrometers using Bi 2 O 2 Se as the only source. However, the high mobility (>20,000 cm 2 V –1 s –1 ) of Bi 2 O 2 Se leads to a high dark current (over 10 –7 A at 1 V), , and the large charge carrier concentration (∼10 18 –10 20 cm –3 ) at room temperature with a high threshold results in a high static power consumption of the photodetector .…”