Impact of thermal oxidation on the electrical transport and chemical & electronic structure of the GaN film grown on Si and sapphire substrates

Gallium oxide (Ga2O3) has emerged as a fourth-generation semiconductor for futuristic device requirements. Integration of Ga2O3 with industry-viable gallium nitride (GaN) can provide a pathway to design efficient device technology. In this paper, we design Ga2O3/GaN heterointerface by using a simple thermal annealing method under an oxygen-rich environment. Thermal annealing at 850 °C for 5 h results in a good yield of Ga2O3 from surficial GaN which was grown on sapphire and Si substrates. Surface morphology revealed a nanorod structure-based Ga2O3 on the GaN surface grown on industrial compatible Si substrate. XPS measurements provide a quantitative understanding of the heterostructure, where 84.62% and 70.92% of surficial GaN is converted into Ga2O3. Besides, the valence band maximum is shifted to a higher energy side in comparison to bare GaN samples. This helps in understanding the device physics of the grown heterostructures. Current-Voltage (I–V) characteristics revealed Schottky behaviour where the Schottky barrier height is increased after thermal annealing of the GaN films. Temperature correlated I–V characteristics suggest that the thermally annealed GaN films are stable up to 300 °C. These material structures can potentially be used in the high-temperature applications for power devices, optoelectronics, and sensing applications.