On the importance of Ni–Au–Ga interdiffusion in the formation of a Ni–Au/p-GaN ohmic contact
Abstract
High-resolution transmission electron microscopy (TEM) coupled to energy dispersive X-ray spectroscopy (EDX) is used to clarify the exact role of Ni–Au–Ga interdiffusion mechanisms taking place during rapid thermal annealing under an oxygen atmosphere of a Ni–Au/p-GaN contact. It is shown that oxygen-assisted, Ni diffusion to the top surface of the metallic contact through the formation of a nickel oxide (NiOx) is accompanied by Au diffusion down to the GaN surface and by Ga out-diffusion through the GaN/metal interface. Electrical characterizations of the contact by a transmission line method show that an ohmic contact is obtained as soon as a thin, Au–Ga interfacial layer is formed, even after complete diffusion of Ni or NiOx to the top surface of the contact. Our results clarify that the presence of Ni or NiOx at the interface is not the main origin of the ohmic-like behavior in such contacts. Auto-cleaning of the interface during the interdiffusion process may play a role, but TEM-EDX analysis evidences that the creation of Ga vacancies associated with the formation of a Ga–Au interfacial layer is crucial for reducing the Schottky barrier height and maximizing the amount of current flowing through the contact.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (16)
Jules Duraz
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
Hassen Souissi
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
Maksym Gromovyi
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
David Troadec
Institut d’Electronique, de Microélectronique et de Nanotechnologie, IEMN, UMR 8520, CNRS, Université de Lille 2 , 59652 Villeneuve d’Ascq,
Téo Baptiste
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
Géraldine Hallais
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
Nathaniel Findling
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,
Phuong Vuong
CNRS, Georgia Tech – CNRS International Research Lab 3 , 2958, 2 rue Marconi, 57070 Metz,
Rajat Gujrati
CNRS, Georgia Tech – CNRS International Research Lab 3 , 2958, 2 rue Marconi, 57070 Metz,
Thi May Tran
CNRS, Georgia Tech – CNRS International Research Lab 3 , 2958, 2 rue Marconi, 57070 Metz,
Jean-Paul Salvestrini
Georgia Tech CNRS, IRL 2958, GT-Europe 3 , 57070 Metz,
Maria Tchernycheva
C2N, Université Paris-Saclay 5 , Palaiseau,
Suresh Sundaram
Georgia Institute of Technology, School of Electrical and Computer Engineering 1 , Atlanta, Georgia 30332-0250,
Abdallah Ougazzaden
Georgia Institute of Technology, School of Electrical and Computer Engineering 1 , Atlanta, Georgia 30332-0250,
Gilles Patriarche
Sophie Bouchoule
Centre de Nanosciences et de Nanotechnologies, C2N, UMR 9001, CNRS, Université Paris-Saclay 1 , 91120 Palaiseau,