Effect of oxidation towards interfacial layer of indium tin-oxide nanostructure and p-type gallium nitride / Norhilmi Mohd Zahir

Norhilmi , Mohd Zahir (2023) Effect of oxidation towards interfacial layer of indium tin-oxide nanostructure and p-type gallium nitride / Norhilmi Mohd Zahir. Masters thesis, Universiti Malaya.

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Abstract

A comprehensive study was performed to probe the effect of the substrate temperature and oxygen incorporation on the structure, optical and electrical properties of ITO deposited on p-GaN. A correlation between the kinetics process of ITO deposition and the structure is explained based on the competition among different surface free energies of bixbyite-In2O3 during film thickening. The irregular shape of the as-deposited ITO on p-GaN is also contributed by the larger lattice mismatch of In2O3 and GaN underlayer. A direct correlation among structural, optical and electrical properties was achieved when ITO was deposited at substrate temperatures of 250 °C, 350 °C and 450 °C. These properties fluctuated when the ITO was deposited at a temperature of 550 °C. The resistivity of the ITO starts to increase again after it has reached its lowest value at a substrate temperature of 450 °C. The 450 °C sample exhibits the best performance of all. The ITO/p-GaN and metal/ITO junctions also show that the 450 °C sample experiences the highest conduction band offset energy and the lowest CBM compared to other samples with the additional formation of an oxide layer at the interface. A transport mechanism for the current spreading role of ITO is suggested to follow the concept of interband tunneling. This work demonstrates that it is crucial to properly investigate the behavior and properties of ITO on specific substrates for specific applications to engineering the performance of the application properly.

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