Ohmic contact formation mechanism of Ta/Al/Mo/Au and Ti/Al/Mo/Au metallizations on Al/GaN/GaN HEMTs

Fitih M. Mohammed, Liang Wang, Deepak Selvanathan, Hubert Hu, Ilesanmi Adesida

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

A comparative study of TaAlMoAu and TiAlMoAu metallizations for AlGaNGaN high electron mobility transistors is presented. By the optimization of surface treatment schemes and annealing temperature, contact resistances of 0.172 and 0.228 Ω mm, and specific contact resistivities of 2.96× 10-7 and 1.09× 10-6 Ω cm2 were obtained for TiAlMoAu and TaAlMoAu, respectively. Auger electron spectroscopy (AES), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were utilized to study microstructural changes occurring in the metallization layers as a result of heat treatment. Results indicate dynamic systems of severe intermixing between atoms from the metallization layers and epilayers resulting in changes in surface morphology, as determined by atomic force microscopy (AFM). The formation of intermetallics and interfacial compounds was observed. The combined effect of surface treatment and annealing-induced reaction is proposed as the mechanisms for low-resistance Ohmic contact formation.

Original languageEnglish
Pages (from-to)2330-2335
Number of pages6
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Volume23
Issue number6
DOIs
Publication statusPublished - Nov 2005
Externally publishedYes

Fingerprint

Ohmic contacts
High electron mobility transistors
Metallizing
high electron mobility transistors
surface treatment
electric contacts
annealing
Surface treatment
low resistance
contact resistance
Annealing
Auger spectroscopy
intermetallics
electron spectroscopy
x ray diffraction
heat treatment
Epilayers
atomic force microscopy
Auger electron spectroscopy
Contact resistance

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Surfaces and Interfaces
  • Physics and Astronomy (miscellaneous)

Cite this

Ohmic contact formation mechanism of Ta/Al/Mo/Au and Ti/Al/Mo/Au metallizations on Al/GaN/GaN HEMTs. / Mohammed, Fitih M.; Wang, Liang; Selvanathan, Deepak; Hu, Hubert; Adesida, Ilesanmi.

In: Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, Vol. 23, No. 6, 11.2005, p. 2330-2335.

Research output: Contribution to journalArticle

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AB - A comparative study of TaAlMoAu and TiAlMoAu metallizations for AlGaNGaN high electron mobility transistors is presented. By the optimization of surface treatment schemes and annealing temperature, contact resistances of 0.172 and 0.228 Ω mm, and specific contact resistivities of 2.96× 10-7 and 1.09× 10-6 Ω cm2 were obtained for TiAlMoAu and TaAlMoAu, respectively. Auger electron spectroscopy (AES), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were utilized to study microstructural changes occurring in the metallization layers as a result of heat treatment. Results indicate dynamic systems of severe intermixing between atoms from the metallization layers and epilayers resulting in changes in surface morphology, as determined by atomic force microscopy (AFM). The formation of intermetallics and interfacial compounds was observed. The combined effect of surface treatment and annealing-induced reaction is proposed as the mechanisms for low-resistance Ohmic contact formation.

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