One-dimensional phosphorus chain and two-dimensional blue phosphorene grown on Au(111) by molecular-beam epitaxy

Abstract

Single layer (SL) phosphorus (phosphorene) has drawn considerable research attention recently as a two-dimensional (2D) material for application promises. It is a semiconductor showing superior transport and optical properties. Few-layer or SL black phosphorus has been successfully isolated by exfoliation from bulk crystals and extensively studied thereof for its electronic and optical properties. Blue phosphorus (blueP), an allotrope of black phosphorus where atoms are arranged in a more flat atomic configuration, has been recently suggested by theory to exist in the SL form on some substrates. In this work, we report the formation of a blueP-like epilayer on Au(111) by molecular-beam epitaxy. In particular, we uncover by scanning tunneling microscopy (STM) one-dimensional (1D) atomic chains at low coverage, which develop into more compact islands or patches of 3 3 30 ()  R structure with increasing coverage before blueP-like islands nucleate and grow. We also note an interesting growth characteristic where the 3 3 30 ()  R surface at intermediate coverage tends to phase-separate into locally low-coverage 1D chain and high-coverage blueP-like structures, respectively. This experiment thus not only lends a support of the recently proposed half-layer by half-layer (HLBHL) growth mechanism but also reveals the kinetic details of blueP growth processes. In this Letter, we report the growth of phosphorus by MBE. In particular, we reveal the HLBHL growth characteristics of P on Au(111), conforming to the recent theoretical prediction [19]. By using scanning tunneling microscopy (STM), we further uncover a new one-dimensional (1D) chain structure, which evolves into the 3 3 30 ()  R compact islands or patches with increasing coverage before blueP-like islands nucleate and grow. The latter manifest by the (5  5) reconstruction, similar to that reported earlier [18,20]. More interestingly, we discover that the 3 3 30 ()  R phase at intermediate coverage gives way to the "phase-separated" 3 surfaces consisting of locally low-coverage 1D chains and high-coverage blueP-like islands coexisted side-by-side on the same surface. This finding enriches our understandings of the variant HLBHL growth mechanism and allows one to design various phosphorene architectures by epitaxy for different purposes.Deposition of P and subsequent STM examinations were carried out in a Unisoku UHV system consisted of a sample preparation chamber and an insert of STM facility operated at 77 K. The base pressure was 1 × 10 −10 Torr. Crystalline Au(111) was cleaned by Ar + bombardment (1.0 keV, 5 × 10 −6 Torr) followed by annealing at ~ 600 °C. Phosphorus vapor was generated from thermal decomposition of InP in a standard Knudsen cell operated at ~ 470 °C. The temperature of the substrate was 210 -230 °C. After depositing for a preset period, the sample was immediately transferred to the cooling stage of the STM for surface examinations. Electrochemically etched tungsten tips were used, which were conditioned by heating and/or silve...

2D V‐V Binary Materials: Status and Challenges

“…Various 2D materials, such as graphene, GaSe, HfSe 2 /MoSe 2 , and MoTe 2 /MoS 2 , have been synthesized by MBE method. Specifically, 2D group‐VA materials, such as β‐phosphorene, α‐antimonene, β‐antimonene, and β‐bismuthene, have been reported to be successfully grown by MBE method. Through reflection high‐energy electron diffraction (RHEED) monitoring, the thickness of layers can be controlled precisely, making MBE a promising method for synthesizing 2D materials.…”

Stable, one-dimensional suspended and supported monatomic chains of pnictogens: a metal–insulator framework

“…72 Similar effects have been found for a 1D structure of phosphorus on the Au(111) surface, whereby the formation of the well-defined zigzag chain was hindered. 34 It is therefore important to know whether the properties predicted above for the free-standing chains can be modified when they are grown on specific substrates. To this end, we first examined zigzag monatomic chains placed on their parent 2D monolayers in hexagonal buckled honeycomb (hb) structures; namely P-ZZ on blue phosphorene, As-ZZ on hb-arsenene, Sb-ZZ on hb-antimonene and Bi-ZZ on hb-bismuthenene.…”

“…33 At the same time, Xu et al reported that an ordered 1D structure of adsorbed phosphorus atoms can grow at low coverage on Au(111) through the molecular-beam epitaxy method. 34 The formation of a well-defined zigzag chain is hindered by the strong interaction between P adatoms and Au atoms of the substrate. Bismuth dimers in the nanoline are observed experimentally on the Si(001) surface, 35 or on H passivated Si(100) surfaces.…”

“…Bismuth dimers in the nanoline are observed experimentally on the Si(001) surface, 35 or on H passivated Si(100) surfaces. 36 Very little is known about the monatomic chains of pnictogens (N, P, As, Sb, Bi) 34,37,38 despite their 2D monolayers, multilayers and nanoribbons having received growing interest. [39][40][41][42][43][44][45][46][47][48][49][50][51] In fact, 2D mono-and multilayers of pnictogens offer diverse properties to be used in various applications, such as in topological spintronic devices, biosensors, batteries, thermoelectric devices, nonlinear optics etc.…”

Monolayer, Bilayer, and Heterostructures of Green Phosphorene for Water Splitting and Photovoltaics

“…All these allotropes are semiconducting with bandgap ranging from 0.48 eV for ε-phosphorene to 2.09 eV for octa-phosphorene [17]. Out of all these allotropes, only α-and β-phosphorene have been experimentally realized [18][19][20][21].…”