Investigating Stable Low-Energy Gallium Oxide (Ga2O3) Polytypes: Insights into Electronic and Optical Properties from First Principles.

This study provides a comprehensive analysis of the electronic and optical properties of low-energy gallium oxide (Ga2O3) polytypes not considered earlier. Among these polytypes, the monoclinic structure (ß-Ga2O3) holds significant relevance for both research and practical applications due to its superior stability under typical conditions. The primary aim of this research is to identify new and stable Ga2O3 polytypes that may exist under zero-temperature and zero-pressure conditions. To achieve this objective, we employ the VASP code to investigate electrical and optical properties, as well as stability assessments. Additionally, we examine phonon and thermal properties, including heat capacity, for all polytypes. This study also encompasses the computation of full elastic tensors and elastic moduli for all polytypes at 0 K, with Poisson's and Pugh's ratios confirming their ductile nature. Furthermore, we present the first ever report on the Raman- and infrared (IR)-active modes of these stable Ga2O3 polytypes. Our findings reveal that these mechanically and dynamically stable Ga2O3 polytypes exhibit semiconductive properties, as evidenced by electronic band structure investigations. This research offers valuable insights into the optical characteristics of Ga2O3 polytypes with potential applications spanning various fields.

Structural, Electronic Properties, and Relative Stability Studies of Low-Energy Indium Oxide Polytypes Using First-Principles Calculations.

Materials made of indium oxide (In2O3) are now being used as a potential component of the next generation of computers and communication devices. Density functional theory is used to analyze the physical, electrical, and thermodynamical features of 12 low-energy bulk In2O3 polytypes. The cubic structure In2O3 is majorly used for many of the In2O3-based transparent conducting oxides. The objective of this study is to explore other new stable In2O3 polytypes that may exist. The structural properties and stability studies are performed using the Vienna ab initio simulation package code. All the In2O3 polytypes have semiconductive properties, according to electronic band structure investigations. The full elastic tensors and elastic moduli of all polytypes at 0 K are computed. Poisson's and Pugh's ratio confirms that all stable polytypes are ductile. The phonon and thermal properties including heat capacity are obtained for mechanically stable polytypes. For the first time, we report the Raman and infrared active modes of stable polytypes.