Controlling magnetic-semiconductor properties of the Si- and Al-doped blue phosphorene monolayer

Doping has been widely employed as an efficient method to diversify the materials properties. In this work, the structural, magnetic, and electronic properties of pristine, aluminum(Al)-, and silicon(Si)-doped blue phosphorene monolayer are investigated using first-principles calculations. Pristine monolayer is a non-magnetic wide gap semiconductor with a band gap of 1.81 eV. The 1Si-doped system is a ferromagnetic semiconductor. However, the magnetism is turned off when increasing the dopant composition with small Si-Si distance. Further separating the dopants recovers step by step the magnetic properties, and an antiferromagnetic(AFM)-ferromagnetic(FM) state transition will take place at large dopants separation. In contrast, Al doping retains the non-magnetic semiconductor behavior of blue phosphorene. However, significant energy gap reduction is achieved, where this parameter exhibits a strong dependence on the dopant concentration and doping configuration. Such control may also induce the indirect-direct gap transition. Our results introduce prospective two-dimensional (2D) materials for applications in spintronic and optoelectronic nano devices, which can be realized and stabilized in experiments as suggested by the calculated formation and cohesive energies.

Engineering the Band Structures of Zigzag Blue Phosphorene and Arsenene Nanoribbons by Incorporating Edge Corrugations: A First Principles Exploration

Using first principles calculations, we have presented a short study on modulation of band structures and electronic properties of zigzag blue phosphorene (ZbPNR) and arsenene nanoribbons (ZANR) by etching the edges of NRs. We have taken the width of both NRs as N = 8 and corrugated the edges in a cosine-like manner. Optimizing every structure and further investigating their stabilities, it was seen that both the etched NRs are energetically feasible. From the computed band structures, the band gaps were seen to be increased for both the NRs on increasing number of etched layers and direct gap semiconductor nature was recorded. Highest energy gap observed were 2.26 and 2.41 eV for ZbPNR and ZANR, respectively. On further application of electric field, we observed the very interesting semiconductor-to-metallic property transition which was explained by wave function plots. Being elements of same group, a similar trend of band gaps modulations was observed for both NRs. This fascinating method of electronic property tuning of the studied NRs can be useful in various nanoscale electronic applications.

Blue and black phosphorene on metal substrates: a density functional theory study

We have performed density functional theory calculations to study blue phosphorene and black phosphorene on metal substrates. The substrates considered are the (111) and (110) surfaces of Al, Cu, Ag, Ir, Pd, Pt and Au and the (0001) and (10$\bar{1}$0) surfaces of Zr and Sc. The formation energy $E_{\rm F}$ is negative (energetically favorable) for all 36 combinations of overlayer and substrate. By comparing values of $\Delta{\Omega}$, the change in free energy per unit area, as well as the overlayer-substrate binding energy $E_{\rm b}$, we identify that Ag(111), Al(110), Cu(111), Cu(110) and possibly Au(110) may be especially suitable substrates for the synthesis and subsequent exfoliation of blue phosphorene, and the Ag(110) and Al(111) substrates for the synthesis of black phosphorene. However, these conclusions are drawn assuming the source of P atoms is bulk phosphorus, and can alter upon changing synthesis conditions (chemical potential of phosphorus). Thus, when the source of phosphorus atoms is P$_4$, blue phosphorene is favored only over Pt(111). We find that for all combinations of overlayer and substrate, the charge transfer per bond can be captured by the universal descriptor $\mathcal{D} = \Delta \chi/\Delta \mathcal{R}$, where $\Delta \chi$ and $\Delta \mathcal{R}$ are, respectively, the differences in electronegativity and atomic size between phosphorus and the substrate metal.

Tuning the electronic and magnetic properties of defect blue phosphorene by the adsorption of nonmetal atoms

Based on the first principles of density functional theory, the adsorption of nonmetallic atoms on the surface of defective blue phosphorene was investigated. The results show that the most stable sites of different nonmetallic atoms on the defect blue phosphorene are different. The nonmetal (B, C, N, O) atoms were adsorbed on SV and SW defects blue phosphorene respectively. It was observed that B, N adsorbed SV defect blue phosphorene systems exhibited semiconducting behavior, whereas O adsorbed SV defect blue phosphorene system exhibited metallic behavior, and C adsorbed SV defect blue phosphorene system exhibited magnetic semiconducting behavior. For SW defect blue phosphorene, the results show that B, N, adsorbed SW defect blue phosphorene showed magnetic semiconductor behavior, while C, O adsorbed SW defect blue phosphorene showed semiconductor behavior.