Composition and Interface Chemistry Dependence in Ohmic Contacts to GaN HEMT Structures on the Ti/Al Ratio and Annealing Conditions

Lilyana Kolaklieva; Roumen Kakanakov; Plamen Stefanov; Volker Cimalla; S. Maroldt; Oliver Ambacher; Katja Tonisch; Florentina Niebelschütz

doi:10.4028/www.scientific.net/MSF.615-617.951

Paper Titles

GaN Epitaxial Growth on Sapphire Substrate with Al Buffer Layer Prepared by E-Beam Evaporation
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Structural Characterization of GaN Epitaxial Layers Grown on 4H-SiC Substrates with Different Off-Cut
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Comparative Study of 3C-GaN Grown on Semi-Insulating 3C-SiC/Si(100) Substrates
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Phase Formation in Ti-Al-N MAX-Phase Contacts to GaN
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Composition and Interface Chemistry Dependence in Ohmic Contacts to GaN HEMT Structures on the Ti/Al Ratio and Annealing Conditions
p.951

Process Parameters Influence on Specific Contact Resistance (SCR) Value for TiAl Ohmic Contacts on GaN Grown on Sapphire
p.955

Electrical Properties of Ni/GaN Schottky Contacts on High-Temperature Annealed GaN Surfaces
p.959

High-Breakdown-Voltage GaN Vertical Schottky Barrier Diodes with Field Plate Structure
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Influence of Thermal Annealing on Ohmic Contacts and Device Isolation in AlGaN/GaN Heterostructures
p.967

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Composition and Interface Chemistry Dependence in Ohmic Contacts to GaN HEMT Structures on the Ti/Al Ratio and Annealing Conditions

Abstract:

Electrical, thermal and chemical properties of Ti/Al/Ti/Au ohmic contacts with different former Ti-Al ratio are investigated for application in GaN HEMTs. Lowest resistivity of 4.22x10-5 Ω.cm2 has been obtained to the channel of the HEMT structure. It is found out that the initial Ti/Al ratio influences the optimal annealing temperature at which the lowest resistivity is obtained and the element distribution and interface chemistry of the annealed contacts. XPS analysis revealed two compounds contributing to ohmic properties: an intermetal compound AlAu2 in the contact layer and a semimetal TiN at the interface with GaN.