In this study, the current density-voltage (J-V) characteristic of Schottky diodes of indium-tin-oxide (ITO) contacts to p-type GaN (p-GaN) has been investigated. The calculated barrier-height value of ITO/p-GaN samples using the thermionic field-emission (TFE) model is 3.2 eV, which implies that the work function of ITO is equal to 4.3 eV. The result is supported by J-V measurements of ITO/n-type GaN Schottky diodes. On the other hand, the barrier height of ITO/p-GaN was also determined from x-ray photoelectron spectroscopy (XPS) data. The analysis of the XPS spectral shifts indicated that this observed barrier-height value of ITO/p-GaN by XPS is in good agreement with the value of 3.2 eV obtained from J-V measurements.
The mechanism of ohmic contact degradation for the oxidized Au/Ni/Mg-doped GaN under various annealing times has been investigated. According to the results from x-ray photoelectron spectroscopy and the Cserveny’s concept, we found that an increase of hole concentration of NiOx would lead to the increasing barrier height and the increasing specific contact resistance (ρc) of oxidized Au/Ni/Mg-doped GaN. This suggests that the NiOx plays an important role in increasing (or reducing) the ρc of oxidized Au/Ni/Mg-doped GaN.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.