TEM studies of multilayer ohmic contacts to n-type AlGaN/GaN

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Fay, Mike W. ; Moldovan, Grigore ; Harrison, Ian ; Balmer, R.S. ; Soley, D.E.J. ; Hilton, K.P. ; Hughes, B.T. ; Uren, M.J. ; Martin, T. ; Brown, Paul D. (2003)
  • Publisher: IOP Publishing Ltd

Ti and Pd barrier layers between the Al/Ti diffusion couple and the Au capping layer of multilayer ohmic contacts to n-type AlGaN/GaN field effect transistors were found to be ineffective in preventing the diffusion of Au to the AlGaN following high temperature rapid thermal annealing. The formation of a band of TiN grains at the contact/AlGaN interface is responsible for the activation of the contact. The presence of interfacial Au and threading dislocations are implicated in the formation of additional Ti-nitride inclusions into the AlGaN, although these do not appear to disrupt the Ti-nitride layer at the original contact/nitride interface, nor significantly influence the contact resistance.
  • References (1)

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