Origins of Negative Differential Resistance in N-doped ZnO Nano-ribbons: Ab-initio Investigation

Realization of efficient and selective NO and NO2 detection via surface functionalized h-B2S2 monolayer

In the ever-growing field of two-dimensional (2D) materials, the boron-sulfide (B2S2) monolayer is a promising new addition to MoS2-like 2D materials, with the boron (a lighter element) pair (B2 pair) having similar valence electrons to Mo. Herein, we have functionalized the h-phase boron sulfide monolayer by introducing oxygen atoms (Oh-B2S2) to widen its application scope as a gas sensor. The charge carrier mobilities of this system were found to be 790 × 102 cm2 V-1 s-1 and 32 × 102 cm2 V-1 s-1 for electrons and holes, respectively, which are much higher than the mobilities of the MoS2 monolayer. The potential application of the 2D Oh-B2S2 monolayer in the realm of gas sensing was evaluated using a combination of density functional theory (DFT), ab initio molecular dynamics (AIMD), and non-equilibrium Green's function (NEGF) based simulations. Our results imply that the Oh-B2S2 monolayer outperforms graphene and MoS2 in NO and NO2 selective sensing with higher adsorption energies (-0.56 and -0.16 eV) and charge transfer values (0.34 and 0.13e). Furthermore, the current-voltage characteristics show that the Oh-B2S2 monolayer may selectively detect NO and NO2 gases after bias 1.4 V, providing a greater possibility for the development of boron-based gas-sensing devices for future nanoelectronics.

Nitrogen-doped zinc oxide nanoribbons for potential resonant tunneling diode applications

Armchair ZnONRs doped with nitrogen are investigated in the current manuscript for possible applications based on negative differential resistance (NDR). To conduct the theoretical research, we use density functional theory (DFT) in conjunction with the non-equilibrium Green's function (NEGF) formalism to carry out first principles computations. Pristine ZnONR (P-ZnONRs) is a semiconductor with a wide energy bandgap (E_g) of 2.53 eV. However, one edge N-doped ZnONRs (S_N-ZnO) and both edge N-doped ZnONRs (D_N-ZnO) are metallic. Partial density of states (PDOS) reveals that the metallicity is caused by the doped nitrogen atom. The transport characteristics analysis revealed the negative differential resistance (NDR) characteristics in the N-doped ZnONRs. The peak-to-valley current ratios (PVCR) are computed and measured to be 4.58 × 10²¹ and 1.83 × 10²² for S_N-ZnO and D_N-ZnO, respectively. The obtained findings suggest the significant potential of armchair ZnONRs for NDR-based applications such as switches, rectifiers, oscillators, memory devices, etc.