Epitaxial Growth of Few‐Layer Black Phosphorene Quantum Dots on Si Substrates

Abstract

antimonene, [10,11] and tellurene, [12] etc. Each invokes different synthesis methods pertaining to their intrinsic structures and properties. Nonetheless, for further practical applications, such as sensors, transistors, lasers, and energy storage, the success of each of those "enchanted" materials depends on the development of quality-controlled, efficient and scalable fabrication methods. Epitaxial growth, e.g., by chemical vapor deposition or molecular beam epitaxy (MBE), has been widely used for two-dimensional (2D) material synthesis, including graphene, silicene, germanene, and MoS 2 . [13][14][15][16] BP nanosheets, as a relatively new member of the 2D family since 2014, have risen to the scientific limelight since its first fabrication by exfoliation. [8,9] BP possesses intriguing properties, such as bandgap tunability by layer thickness, doping, and strain, etc.; in-plane anisotropy, particularly anisotropy in electron conductance; and high carrier mobility. [17,18] However, the fabrication of BP is still limited to poorly controlled mechanical and liquid exfoliations [19][20][21][22][23] and phase transition under harsh conditions. [24,25] Blue phosphorene, another allotrope of BP, has been fabricated using the MBE method. [26,27] There is no report on the synthesis of BP using a bottom-up method, to the best of our knowledge. Particularly, considerable efforts are needed to understand the formation mechanism of the BP, and its stability and sensitivity to substrate for continuous growth.For the first time, we demonstrate the synthesis of black phosphorene quantum dots (BPQDs), as an attempt for above mentioned challenges, i.e., phase transition under the harsh conditions, of epitaxial growth of 2D BP, from white phosphorus directly on 3 in. Si substrates by MBE. Epitaxial BPQDs were grown on fully deoxidized Si(111) at 20 °C and Si(100) covered with native oxide at 15 °C, respectively. The as-grown BPQDs were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy with BP fingerprint peaks. Uniform and pyramid-shaped BPQDs were obtained on Si(111) substrates, with an average radius of 27.5 ± 5 nm and height of 3.1 ± 0.6 nm. According to the AFM images, BPQDs preferably crystallized at the steps on the Si(111) surface. Comparatively, BPQDs on the nondeoxidized Si(100) substrate without observable surface steps, Elemental 2D materials, such as silicene, germanene, and stanene, are synthesized by molecular beam epitaxy (MBE). However, the epitaxial growth of black phosphorene is challenging to date. Herein, the successful MBE growth of few-layer black phosphorene quantum dots (BPQDs) directly on Si substrates at relatively low temperature using white phosphorus as the precursor is reported. The formation of black phosphorene is confirmed by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, in combination with density functional theory (DFT) calculations. Uniform and pyramid-shaped BPQDs with an average radius of 27.5 ...

Ambipolar and Robust WSe2 Field‐Effect Transistors Utilizing Self‐Assembled Edge Oxides

“…Raman spectroscopy, sensitive to crystal structures, carrier doping and vacancy defects, was employed to further identify air-exposure effects on O-WSe2. [35][36][37][38] In order to avoid phonon vibration from edge oxides or surface spots, the Raman scattering measurements for O-WSe2 nanoflakes were carefully performed at the inner and clean sites. Excitation power was controlled around 0.1 mW to avoid possible local thermal oxidation.…”

Recent Advances in 2D MXenes for Photodetection

“…[ 5–7 ] Since the first exfoliation of graphene, not only novel materials, including black phosphorene, silicene, stanene, and h‐BN, has emerged, but also the strong interests in transition metal dichalcogenides (TMDs) have resurged. [ 8–11 ] As a relatively new branch of 2D materials, transition metal carbides, carbonitrides, and nitrides were first discovered and termed MXenes by Barsoum et al in 2011. [ 12 ]…”

Thermoelectric effect and devices on IVA and VA Xenes

“…113 Even poorly thermally stable BP quantum dots were successfully realized by this method. 114 Recently, plumbene, the last IVA group cousin of graphene was epitaxially grown by segregation on a Pd-Pb (111) alloy surface. 115 In addition, Van der Waal epitaxial growth via vapor transport has been shown to be suitable for the growth of compounds with layered structures 116 and good stability.…”

“…Most elemental 2D materials have been successfully synthesized by MBE, from graphene to silicene, 84 germanene, 111 antimonene 112 and bismuthene 113 . Even poorly thermally stable BP quantum dots were successfully realized by this method 114 . Recently, plumbene, the last IVA group cousin of graphene was epitaxially grown by segregation on a Pd‐Pb (111) alloy surface 115 .…”