Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry

N. Thierry-Jebali (1, 2) , O. Menard (2, 3) , R. Chiriac (1) , E. Collard (2) , C. Brylinski (1) , Frédéric Cayrel (3) , D. Alquier (3)

1 LMI - Laboratoire des Multimatériaux et Interfaces
2 ST-TOURS - STMicroelectronics [Tours]
3 GREMAN - UMR 7347 - GREMAN (matériaux, microélectronique, acoustique et nanotechnologies)

This work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n+-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500°C and the other one around 660°C. They can be respectively attributed to Al3Ti and Al2Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reac-tions. Lowest contact resistance is well correlated with the presence of Al3Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n+-GaN were annealed from 400°C to 650°C. Specific Contact Resistivity (SCR) values stay in the mid 10-5 Ω.cm² range for annealing temperatures between 450°C and 650°C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together.

Mots clés: Gallium Nitride; Differential Scanning Calorimetry; ohmic contact; TiAl

Domaines: Electronique; Matériaux

N. Thierry-Jebali, O. Menard, R. Chiriac, E. Collard, C. Brylinski, et al.. Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry. physica status solidi (c), 2011, 8 (2), pp.447--449. ⟨hal-00763471⟩