چكيده به لاتين
In recent years, investigation of transport properties, and tunneling procedures through potential barriers based on two-dimensional materials such as graphene have been widely concerned. However, the limitation of the zero band gap of graphene has restricted using them in nano-electronic circuits. Phosphorene as a semiconductor with high carrier mobility, tunable bandgap, and anisotropic properties could be a more proper candidate for use in semiconductors. In this thesis, the electronic and spintronic properties of phosphorene nanoribbons have been investigated based on the transfer matrix method theoretically. Since the generation of a spin-polarized current is a fundamental prerequisite for the construction of spintronic devices, therefore, the transmission probability in the presence and absence of the Rashba effect, the exchange field, and the bias voltage by using the transfer matrix, has been obtained for a single rectangular barrier and a rectangular superlattice. The results show that 100% spin polarization can be achieved due to the absence of the Klein paradox in phosphorus systems. In addition, the results show that by controlling the Rashba strength and bias voltage, the phosphorene nanoribbon can act as a spin filter for the input current. The results showed that with increasing the number of barriers to twenty, the complete transmission probability occurs in the zero incoming angles. It was also shown that with increasing the number of barriers, the complete transmission probability occurs at lower landing energies. In addition, it was observed that by increasing the number of barriers, the complete transmission probability can be observed in the width of smaller barriers. In addition, the results showed that the transmission probability and spin polarization can be increased by adjusting the width of the barrier in the presence of an exchange field created by placing a ferromagnetic insulator on the phosphorene layer in the barrier area. Also, by increasing the number of barriers, the full transmission probability occurs in the presence of the exchange field for the zero landing angle, while the transmission probability for this angle is reported to be low in a single barrier. Also, the results in the presence of the exchange field showed that the full transmission probability and 100% spin polarization occurred for a larger number of incident energies. In addition, it was observed that the full transmission probability in the presence of the exchange field has happened at the smaller incident energies by increasing the number of barriers. The results showed that in the presence of the exchange field, the best results occurred in twenty barriers. The results show that the number of barriers in the superlattice structure plays a dominant role in output spin polarization in the presence of the Rashba effect, which can be used in designing optimized spintronic devices. In addition, by controlling the Rashba strength, an incident spin-up electron can be transmitted as a spin-down electron. Also, controlling the Rashba strength enables the conversion of the unpolarized incident electronic beam (with zero spin polarization) into an arbitrary output spin polarization, which plays a significant role in qubit circuits. Further, the results showed that in the presence of the Rashba effect, the best results occur in five barriers.
