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Composition and interface chemistry dependence in ohmic contacts to GaN HEMT structures on the Ti/Al ratio and annealing conditions

Einfluss des Al/Ti-Verhältnisses und der Temperbedingungen auf die Zusammensetzung und die Grenzflächenreaktionen von Ohmschen Kontakten für GaN HEMTs
: Kolaklieva, L.; Kakanakov, R.; Stefanov, P.; Cimalla, V.; Maroldt, S.; Ambacher, O.; Tonisch, K.; Niebelschütz, F.


Amador Pérez, T.:
Silicon carbide and related materials 2008 : ECSCRM 2008, selected, peer reviewed papers from the 7th European Conference on Silicon Carbide and Related Materials, September 7 - 11, Barcelona, Spain
Stäfa-Zürich: Trans Tech Publications, 2009 (Materials Science Forum 615-617)
ISBN: 0-87849-334-4
ISBN: 978-0-87849-334-0
European Conference on Silicon Carbide and Related Materials (ECSCRM) <7, 2008, Barcelona>
Conference Paper, Journal Article
Fraunhofer IAF ()
high electron mobility transistror; HEMT; ohmic contact; Ohmscher Kontakt; sputter depth profiling; Sputtertiefenprofilierung; diffusion

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(exp -5) Ohm.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.