Zinc oxide (ZnO) is a multifunctional material with wide applications in electronics, optoelectronics, biomedicine, and energy technologies. It has a wide bandgap and high exciton binding energy, making it suitable for various devices. However, high-quality ZnO growth and characterization remain challenging. Recent advancements in growth techniques, such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD), have enabled the synthesis of high-quality ZnO films, nanostructures, and bulk materials. These techniques allow for precise control over the material's properties, including bandgap engineering and doping. Native defects in ZnO, such as oxygen vacancies and zinc interstitials, significantly affect its electrical and optical properties. Understanding and controlling these defects is crucial for improving the performance of ZnO-based devices. p-type doping of ZnO remains a challenge due to the difficulty in achieving stable and high-conductivity p-type materials. Various elements, including group-V, group-I, and group-IB elements, have been explored for p-doping, with some showing promising results. Codoping strategies have also been considered to enhance p-type conductivity and structural stability. Bandgap engineering of ZnO through alloying with MgO or CdO has enabled the tuning of its optical and electronic properties. These alloys can exhibit a wide range of bandgaps, from 2.3 to 4.0 eV, making them suitable for various applications. ZnO-based devices, such as spintronic materials, neuromorphic computing components, and photovoltaic cells, are being explored for their unique properties. ZnO's ability to convert heat energy into electricity and its potential in spintronics and quantum computing make it a promising candidate for next-generation technologies. The combination of its electrical, thermoelectric, and optical properties positions ZnO as a key material for future electronic and energy applications.Zinc oxide (ZnO) is a multifunctional material with wide applications in electronics, optoelectronics, biomedicine, and energy technologies. It has a wide bandgap and high exciton binding energy, making it suitable for various devices. However, high-quality ZnO growth and characterization remain challenging. Recent advancements in growth techniques, such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD), have enabled the synthesis of high-quality ZnO films, nanostructures, and bulk materials. These techniques allow for precise control over the material's properties, including bandgap engineering and doping. Native defects in ZnO, such as oxygen vacancies and zinc interstitials, significantly affect its electrical and optical properties. Understanding and controlling these defects is crucial for improving the performance of ZnO-based devices. p-type doping of ZnO remains a challenge due to the difficulty in achieving stable and high-conductivity p-type materials. Various elements, including group-V, group-I, and group-IB elements, have been explored for p-doping, with some showing promising results. Codoping strategies have also been considered to enhance p-type conductivity and structural stability. Bandgap engineering of ZnO through alloying with MgO or CdO has enabled the tuning of its optical and electronic properties. These alloys can exhibit a wide range of bandgaps, from 2.3 to 4.0 eV, making them suitable for various applications. ZnO-based devices, such as spintronic materials, neuromorphic computing components, and photovoltaic cells, are being explored for their unique properties. ZnO's ability to convert heat energy into electricity and its potential in spintronics and quantum computing make it a promising candidate for next-generation technologies. The combination of its electrical, thermoelectric, and optical properties positions ZnO as a key material for future electronic and energy applications.