Thermal spin molecular logic gates modulated by an electric field

Logic gates are fundamental structural components in all modern digital electronic devices. Here, nonequilibrium Green's functions are incorporated with the density functional theory to verify the thermal spin transport features of the single-molecule spintronic devices constructed by a single molecule in series or parallel connected with graphene nanoribbons electrodes. Our calculations demonstrate that the electric field can manipulate the spin-polarized current. Then, a complete set of thermal spin molecular logic gates are proposed, including AND, OR, and NOT gates. The mentioned logic gates enable different designs of complex thermal spin molecular logic functions and facilitate the electric field control of thermal spin molecular devices.

Electronic and optical properties of GaN–MoS2 heterostructure from first-principles calculations

Heterostructures(HSs)have attracted significant attention because of their interlayer van der Waals interactions.The electronic structures and optical properties of stacked GaN-MoS2 HSs under strain have been explored in this work using density functional theory.The results indicate that the direct band gap(1.95 e V)of the Ga N-MoS2 HS is lower than the individual band gaps of both the GaN layer(3.48 e V)and the MoS2 layer(2.03 eV)based on HSE06 hybrid functional calculations.Specifically,the GaN-MoS2 HS is a typical type-II band HS semiconductor that provides an effective approach to enhance the charge separation efficiency for improved photocatalytic degradation activity and water splitting efficiency.Under tensile or compressive strain,the direct band gap of the GaN-MoS2 HS undergoes redshifts.Additionally,the GaN-MoS2 HS maintains its direct band gap semiconductor behavior even when the tensile or compressive strain reaches 5%or-5%.Therefore,the results reported above can be used to expand the application of Ga N-MoS2 HSs to photovoltaic cells and photocatalysts.

First-principles study of p-type ZnO by S-Na co-doping

Using the first-principles method based on the density functional theory, the formation energy, electronic structures of S-Na co-doping in ZnO were calculated. The calculated results show that Nazn-So have smaller formation energy than Nain-So in energy ranges from -3.10 to 0 eV of/Zo, indicating that it opens up a new opportunity for growth the p-type ZnO. The band structure shows that the Nazn system is a p-type direct-band-gap semiconductor material and the calculated band gap （0.84 eV） is larger than pure ZnO （0.74 eV）. The Nazn-So system is also a p-type semiconductor material with a direct band gap （0.80 eV）, The influence of S-Na co-doping in ZnO on p-type conductivity is also discussed. The effective masses of Nazn-So are larger than effective masses of Nazn and the Nazn-So have more hole carriers than Nazn, meaning the hole in the Nazn-So system may have a better carrier transfer character. So we inferred that Nazn-So should be a candidate of p-type conduction.