A two-dimensional analytical model of double-gate(DG) tunneling field-effect transistors(TFETs) with interface trapped charges is proposed in this paper. The influence of the channel mobile charges on the potential profile is also taken into account in order to improve the accuracy of the models. On the basis of potential profile,the electric field is derived and the expression for the drain current is obtained by integrating the BTBT generation rate. The model can be used to study the impact of interface trapped charges on the surface potential, the shortest tunneling length, the drain current and the threshold voltage for varying interface trapped charge densities, length of damaged region as well as the structural parameters of the DG TFET and can also be utilized to design the charge trapped memory devices based on TFET. The biggest advantage of this model is that it is more accurate,and in its expression there are no fitting parameters with small calculating amount. Very good agreements for both the potential, drain current and threshold voltage are observed between the model calculations and the simulated results.
First-principles calculations are used to investigate the migration path of Ag in the Hf O2-based resistive random access memory(Re RAM). The formation energy calculation suggests that there are two different sites(site 1 and site 3) for the incorporation of Ag atoms into the Hf O2 unit cell. Thermodynamic analysis shows that the motion of Ag atom in the Hf O2 supercell appears to be anisotropic, which is due to the fact that the Ag atom at site 3 moves along the [1ˉ11] orientation,but the Ag atom at site 1 moves along the [001] orientation. The migration barriers of the Ag atoms hopping between neighboring unit cells are calculated along five different orientations. Difficulty in producing motion of the Ag atom varies with the migration barrier: this motion is minimized along [1ˉ11] orientation. Furthermore, The optimal circulation path for Ag migration within the Hf O2 supercells is obtained, and is found to be approximately along the [1ˉ11] orientation.Therefore, it is proposed that the positive voltage should be applied along this orientation, the conduction filament may form more easily, which could improve the response time and reduce the power consumption in Re RAM applications.
