Auger electron spectroscopy of Au/NiO contacts on p-GaN annealed in N2 and O2+ N2 ambients

Ohmic Contacts to p-GaN Using Au/Ni-Zn-O Metallization

“…Promising results have been reached while examine the effect of a NiO x layer with a low concentration of oxygen upon the electrical properties of ohmic contacts Au/NiO x /p-GaN [19]. It was found that a low-resistance ohmic contact is provided by Au/NiO x layers deposited by reactive magnetron sputtering and annealed not only in oxygen but also in nitrogen, in the latter case the results are even better.…”

Ohmic contacts to p-GaN Using Au/Ni-Mg-O Metallization

“…The value of the contact resistivity is lower than in the case of the Au/Ni-O x /p-GaN contact. Increasing the oxygen concentration in the ambient atmosphere during depositing the Ni-Mg layer struct brought about a rise of the contact resistivity of the Au/Ni-Mg-O x /p-GaN structure, similarly like in the case of Au/Ni-O x /p-GaN contacts [14]. Figure 1(a) shows AES depth profiles of the asdeposited Au/Ni-Mg-O x /p-GaN structure.…”

“…The observed distribution of the components in the contact, being a consequence of annealing, can be explained by a polycrystalline structure of the contact layer composed of Au, Ni, MgO and NiO crystallites. Our study of the Au/NiO x /p-GaN contact [14] revealed that annealing in N 2 caused reconstruction of the contact into Au/p-NiO/p-GaN and Ni/p-NiO/p-GaN and ohmic properties of the contacts were predetermined by creating a thin NiO oxide layer on the metal/pGaN interface. In our view the ohmic nature of the Au/Ni-Mg-O x /p-GaN contact structure may be similarly like in the previous case related to the existence of a metal/p-NiO/p-GaN contact scheme.…”

“…The almost identical concentrations and gradients of Mg and O in the contact structure point at creation of MgO that precipitates mainly in the region of the initial interfaces and on the surface. Based on our previous work [14] we believe that oxygen interacts with Ni giving rise to NiO and, due to annealing, the initial Ni-Mg-O x layer is transformed to a mixture of Ni, NiO and MgO crystals. The observed distribution of the components in the contact, being a consequence of annealing, can be explained by a polycrystalline structure of the contact layer composed of Au, Ni, MgO and NiO crystallites.…”

“…Lately [14] it has been found by studying the influence of the NiO x layer on the electrical characteristics of the Au/NiO x /p-GaN ohmic contacts that the Au/NiO x /p-GaN structure with a low content of oxygen in NiO x , deposited on p-GaN by reactive magnetron sputtering and annealed in the mixture of O 2 + N 2 or N 2 ambient, provided a low resistance ohmic contact. Slightly higher contact resistances in samples annealed in O 2 +N 2 can be explained by a smaller effective area of the contact at the layer/p-GaN interface due to created voids.…”