Bandgap scaling and negative differential resistance behavior of zigzag phosphorene antidot nanoribbons (ZPANRs)

Gap engineering effects on transport and tunneling magnetoresistance properties in phosphorene ferromagnetic/normal/ferromagnetic junction

Tuning the band gap is of utmost importance for the practicality of two-dimensional materials in the semiconductor industry. In this study, we investigate the ballistic transport and the tunneling magnetoresistance (TMR) properties within a modulated gap in a ferromagnetic/normal/ferromagnetic (F/N/F) phosphorene junction. The theoretical framework is established on a Dirac-like Hamiltonian, the transfer matrix method, and the Landauer-Büttiker formalism to characterize electron behavior and obtain transmittance, conductance and TMR. Our results reveal that a reduction in gap energy leads to an enhancement of conductance for both parallel and anti-parallel magnetization configurations. In contrast, a significant reduction and redshift in TMR have been observed. Notably, the application of an electrostatic field in a gapless phosphorene F/N/F junction induces a blueshift and a slight increase in TMR. Furthermore, we found that introducing an asymmetrically applied electrostatic field in this gapless junction results in a significant reduction and redshift in TMR. Additionally, intensifying the applied magnetic field leads to a substantial increase in TMR. These findings could be useful for designing and implementing practical applications that require precise control over the TMR properties of a phosphorene F/N/F junction with a modulated gap.

Two-Dimensional GeC2 with Tunable Electronic and Carrier Transport Properties and a High Current ON/OFF Ratio

In this study, we present that 2D tetrahex-GeC₂ materials possess novel electronic and carrier transport properties based on density functional theory computations combined with the nonequilibrium Green's function method. We show that under the 4% (-4%) in-plane expansion (compression) along the a-direction (b-direction) of the tetrahex-GeC₂ monolayer, the bandgap can be enlarged to a desirable 1.26 eV (1.32 eV), close to that of silicon. The carrier transport properties of both the sub-10 nm tetrahex-GeC₂ monolayer and the bilayer show strong anisotropy within the bias from -1 to 1 V. The current ON (a-direction)/OFF (b-direction) ratio amounts to 10⁵ for the tetrahex-GeC₂ monolayer. A striking negative differential conductance arises with the maximum I_peak/I_valley on the order of 10⁴ under the 4% uniaxial expansion along the b-direction of the tetrahex-GeC₂ monolayer. Overall, the 2D tetrahex-GeC₂ monolayer and bilayer possess highly tunable electronic and carrier transport properties under uniaxial strain, which can be exploited for potential applications in nanoelectronics.

Effect of surface oxidation on the electronic transport properties of phosphorene gas sensors: a computational study

The potential for phosphorene-based devices has been compromised by the material's fast degradation under ambient conditions. Its tendency to fully oxidize under O₂-rich and humid environments, leads to the loss of its appealing semiconducting properties. However, partially-oxidized phosphorene (po-phosphorene), has been demonstrated to remain stable over significantly longer periods of time, thereby enabling its use in sensing applications. Here, we present a computational study of po-phosphorene-based gas sensors, using the Density-Functional-based Tight Binding (DFTB) method. We show that DFTB accurately predicts the bandgap for the pristine material and po-phosphorene, the electronic transport properties of po-phosphorene at different surface oxygen concentrations, and the appropriate trends in Density-of-States (DOS) contributions caused by adsorbed gas molecules, to demonstrate its potential application in the development of gas sensors. Results are compared against the more traditional and expensive Density Functional Theory (DFT) method using generalized gradient approximation (GGA) exchange–correlation functionals, which significantly underestimates the material's bandgap.

Computational study of surface oxidation effects on phosphorene-based gas sensors, and potential for nM L⁻¹ detection and measurement of nitrogen–oxygen moieties.