On the semiconductor to metal transition in a quantum wire: Influence of geometry and laser

The diamagnetic susceptibility and binding energy (BE) of a hydrogenic donor confined in a GaAs/AlGaAs QWW were theoretically studied in this paper under the influences of the applied laser field, QWW geometry, and non-parabolicity using variation technique combined with effective mass approximation. In the first part, the diamagnetic susceptibility and BE of the donor at the ground state are studied as a function of the size of the QWW, geometry, and applied laser field. The results reveal that changing the geometry of QWW enhances the quantum confinement effects. However, increasing the laser field reduces the BE by adding screening effects to the Coulomb interactions. Further, the diamagnetic susceptibility is available with the stability information about the carrier-parent donor system based on the mean square separation between them. It also demonstrates that susceptibility may remain stable regardless of the change in geometry and applied laser field. Thus, the diamagnetic behavior can serve as a better tool to evaluate the stability and Mott transition of donors in QWW. In the second section, the consequences of laser field and geometry on the SMT of confined donors in QWW have been studied. It is observed that the BE of donors remains constant until N similar to 1015 cm-1 beyond which it starts to decrease gradually and vanishes exactly at critical concentration (Nc). However, the diamagnetic susceptibility of the donor has remained constant until reaching Nc, beyond which it turned into a drastic fall, which manifested the SMT in the system. The current work is expected to add a few noteworthy points to the SMT phenomena in nanostructures.

Automated summary

This paper theoretically studies the diamagnetic susceptibility and binding energy of a hydrogenic donor in a GaAs/AlGaAs quantum well wire (QWW) under the influence of laser field, QWW geometry, and non-parabolicity. The results show that changing the QWW geometry enhances quantum confinement effects, while increasing the laser field reduces the binding energy. The diamagnetic susceptibility can serve as a tool to evaluate the stability and Mott transition of donors in the QWW. Furthermore, the study finds that the binding energy remains constant until reaching a critical concentration (Nc), while the diamagnetic susceptibility undergoes a drastic fall after Nc, indicating a Stoner magnet transition (SMT) in the system.