1. Effects of W diffusion barrier on inhibition of AlN formation in Ti/W/Al ohmic contacts on N-face n-GaN
- Author
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Chul Jong Yoo, Buem Joon Kim, Jun Ho Son, Hak Ki Yu, Yang Hee Song, and Jong-Lam Lee
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Diffusion barrier ,Metallurgy ,Wide-bandgap semiconductor ,chemistry.chemical_element ,Tungsten ,Crystallography ,Band bending ,chemistry ,Electrical resistivity and conductivity ,Transmission electron microscopy ,Thermal stability ,Ohmic contact - Abstract
We investigate the effect of W diffusion barrier in Ti/W/Al ohmic contacts formed on N-face n-GaN. The contacts exhibit contact resistivity of as low as 2.3 × 10−4 Ω cm2 and better thermal stability than Ti/Al contacts. Cross-sectional transmission electron microscopy micrographs reveal that in-diffused Al atoms on the n-GaN surface react with N atoms to form an AlN layer in Ti/Al contacts, resulting in upward band bending, and consequently, a high contact resistivity. The use of a 10-nm-thick W layer suppresses the in-diffusion of Al atoms to n-GaN, thereby preventing the formation of AlN and enhancing the thermal stability of Ti/W/Al contacts.
- Published
- 2011
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