Project start: 1.10.2025.

The zinc sulfide (ZnS) and zinc oxide (ZnO) II-VI wide-bandgap semiconductors, exhibit today complementary technological roles. The ZnS excels in optoelectronics (luminescent displays, X-ray screens) and infrared optics (thermal imaging, missile domes), while serving as a solar cell window layer. The ZnO’s versatility spans transparent conductive oxides (doped for displays/solar cells), UV optoelectronics (LEDs, detectors), and piezoelectric devices (sensors, energy harvesters), with biomedical applications. The ZnS dominates infrared/display systems; ZnO extends into multifunctional platforms. Their structural and electronic distinctions highlight complementary roles in advancing modern technology. The primary objective of this project is to investigate the structural and thermodynamic stability of ZnS (sphalerite-type)/ZnO (wurtzite-type) polytypes interfaces using first-principles density functional theory (DFT) calculations. Using DFT calculations accelerated by high-performance computing (HPC), this work will perform atomistic simulations to predict equilibrium structures and emergent properties (e.g., mechanical hardness, electronic band alignment) of ZnS/ZnO polytype heterostructures. The methodology enables ab initio design of interfacial and metastable phases, including unsynthesized configurations, by rigorously modeling structure-property relationships at the quantum-mechanical level. Furthermore, this study aims to elucidate the role of stacking sequences, interfacial strain, and electronic interactions in stabilizing these heterostructures, providing insights into their potential applications in optoelectronic and catalytic systems. Finally, the following issues will be systematically investigated within this project: (i) the role of oxygen impurities in the stability of twin boundaries, (ii) the role of iron atoms in stacking sequences, and (iii) twin boundary stability with sulfur or oxygen via chemical potential and formation enthalpy.