Open AccessLow temperature (down to 450 °C) annealed TiAl contacts on N‐type gallium nitride characterized by differential scanning calorimetry
Author(s) -
ThierryJebali Nicolas,
Menard Olivier,
Chiriac Rodica,
Collard Emmanuel,
Brylinski Christian,
Cayrel Frédéric,
Alquier Daniel
Publication year - 2011
Publication title -
physica status solidi c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 46
eISSN - 1610-1642
pISSN - 1862-6351
DOI - 10.1002/pssc.201000597
Subject(s) - ohmic contact , materials science , differential scanning calorimetry , annealing (glass) , stoichiometry , analytical chemistry (journal) , electrical resistivity and conductivity , gallium nitride , gallium , contact resistance , nitride , calorimetry , atmospheric temperature range , schottky diode , metallurgy , nanotechnology , optoelectronics , chemistry , thermodynamics , layer (electronics) , diode , electrical engineering , physics , engineering , chromatography
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 Al 3 Ti and Al 2 Ti compounds formation. The locations of these peaks provide clear evidence of solid‐solid reactions. Lowest contact resistance is well correlated with the presence of Al 3 Ti 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. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)