Effects of extrinsic point defects in phosphorene: B, C, N, O, and F adatoms

Abstract

Phosphorene is emerging as a promising 2D semiconducting material with a direct band gap and high carrier mobility. In this paper, we examine the role of the extrinsic point defects including surface adatoms in modifying the electronic properties of phosphorene using density functional theory. The surface adatoms considered are B, C, N, O and F with a [He] core electronic configuration. Our calculations show that B and C, with electronegativity close to P, prefer to break the sp 3 bonds of phosphorene, and reside at the interstitial sites in the 2D lattice by forming sp 2 like bonds with the native atoms. On the other hand, N, O and F, which are more electronegative than P, prefer the surface sites by attracting the lone pairs of phosphorene. B, N and F adsorption will also introduce local magnetic moment to the lattice.Moreover, B, C, N and F adatoms will modify the band gap of phosphorene yielding metallic transverse tunneling characters. Oxygen does not modify the band gap of phosphorene, and a diode like tunneling behavior is observed. Our results therefore offer a possible route to tailor the electronic and magnetic properties of phosphorene by the adatom functionalization, and provide the physical insights of the environmental sensitivity of phosphorene, which will be helpful to experimentalists in evaluating the performance and aging effects of phosphorene-based electronic devices. 3Phosphorene is the monolayer form of the black phosphorus. Since the interlayer interaction in the bulk black phosphorus is dominated by the van der Waals forces, phosphorene could be obtained by exfoliating from the bulk lattice 1-4 . In fact, a few layer of phosphorene is successfully exfoliated and exploited for applications in electronic devices 1 .Recently, it has been demonstrated that phosphorene-based transistors possess a larger current on/off ratio compared to graphene-based transistors and higher charge mobility than

Doping behaviors of adatoms adsorbed on phosphorene

“…The total magnetic moment is 1.00 µ B , equal to the results in Ref. . Adsorption of Cl and Br also induces the total magnetic moment of 1.00 µ B , as listed in Table .…”

Tunable photoluminescence from sheet-like black phosphorus crystal by electrochemical oxidation

“…24 However, previous theoretical results suggest that oxygen adsorption may not degrade the phosphorene structure. 21,22 Our results to be presented below indicate that partial oxygen adsorption under natural conditions is different from artificial oxidation and does not modify electronic states and phonon properties of BP. The P and O atomic concentration ratio is 1:0.9 for the pristine BP.…”

“…[19][20][21][22] As confirmed by XPS, the BP oxide prepared electrochemically is inhomogeneous and therefore, different electronic structures are expected at different locations on the single BP oxide crystal. By utilizing the confocal microscopy setup, PL and Raman spectra are acquired from the BP oxide from five random points.…”

“…15 In spite of recent advances, BP remains a relatively unexplored two-dimensional (2D) semiconductor, 16 and a viable approach to tune the electronic structure of BP needs to be developed to widen the applications. Similar to graphene oxide, oxidation of BP may be an effective approach and recent theoretical studies predict that the bandgap of phosphorene oxide depends on the oxygen concentration, [19][20][21][22] thereby suggesting that controlled oxidation can be used to adjust the electronic structures. However, experimental evidence is still lacking.…”

Prospects of spintronics based on 2D materials

“…Interestingly, magnetic moment can also be induced by nonmagnetic dopants such as O, S, Se, C, Si, etc. in black phosphorus as well as blue phosphorus …”