Spin-Orbit Coupling and Piezoelectric Properties of Zinc Oxide Quantum Dots Using First-Principles Calculations

Electronic and Spin-Orbit Coupling (SOC) properties of piezoelectric Zinc Oxide (ZnO) quantum dots (QDs) have been investigated using first-principles calculations. Density Functional Theory (DFT) and non-collinear SOC in Quantum ESPRESSO have been utilized via the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional for the present studies. A significant band splitting has been observed near the valence and conduction band edges for the 5 nm spherical QD and a helical spin texture in the 10 nm QD. Our results show the breaking of Time Reversal Symmetry (TRS) in 10 nm QD due to SOC and enhanced electron mobility in the 5 nm QD, along with a size-dependent piezoelectric response, particularly in the strong confinement regime confirmed by the Valence Force Field (AVFF) model in both 5 and 10 nm QDs. Visualization of the spin polarization was made possible by employing Maximally Localized Wannier Functions (MLWFs). Our investigations have significant practical ramifications for spintronics and quantum information processing.