Abstract
Oxide semiconductors have developed rapidly in a short period of time in various industrial fields due to their ability to be easily manufactured at low temperatures and recoverability of electrical properties. Among these oxide semiconductors, nickel oxide (NiO) is one of the most studied transition metal oxides. NiO is a p-type semiconductor with a wide band gap at room temperature, and has advantages of low toxicity, low cost, and excellent stability. Due to these advantages, NiO is widely used in various industrial fields such as gas sensors. In this paper, various synthesis methods of NiO will be briefly reviewed. Such synthesis methods include organic solvent methods, chemical vapor deposition methods, sol-gel methods, and chemical solution deposition methods. Materials required for each synthesis method, experimental methods, post-processing, and experimental results are briefly described.