Nonalloyed ohmic contact formation in Ti/Al contacts to n-type AlGaN (n-AlGaN) was achieved in this study. The surface chemistry and electrical properties of n-AlGaN surfaces were studied via x-ray photoelectron spectroscopy before and after oxidation and wet chemical treatments. The authors found that changes in the contact resistance are dominated by changes in the Al mole fraction and the interface states. Oxidation and HF and (NH4) 2Sx treatments on n-AlGaN led to an increase in the electron affinity (due to a reduction in the Al content at the n-AlGaN surface) and a reduction in the surface band bending (due to more N vacancies and N vacancies being occupied by S (i.e. donor-like states) than Al vacancies and Ga vacancies (i.e. acceptor-like states) near the n-AlGaN surface region), leading to the nonalloyed ohmic contact formation for the Al/Ti/n-AlGaN sample.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films