Nanostructured antidiffusion layers in contacts to wide-gap semiconductors

Ya. Ya. Kudryk

doi:10.15222/TKEA2013.6.03

Ya. Ya. Kudryk V. Ye. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, Kyiv, Ukraine

DOI: https://doi.org/10.15222/TKEA2013.6.03

Keywords: antidiffusion layer, nanocrystal film, heat stability, wide-gap semiconductor, contact

Abstract

The interrelation between the antidiffusion properties of titanium diboride films and their nanocrystalline structure is investigated. We made a valid assumption that the main reason for degradation of contacts with TiB₂-based diffusion layers is diffusion through the TiB₂ film through dislocations (formed due to stresses that appear in the course of ohmic contact formation) rather than chemical interaction. In that case, increase of mechanical strength of the TiB₂ film at reduction of grain size will affect its diffusion strength more strongly than growth of diffusion penetrability owing to increase of grain boundary role. Our investigations showed that, to ensure maximal mechanical strength and heat stability, the size of nanocrystallites in films forming diffusion barriers has to lie within 3–15 nm. The TiB₂ films with optimal nanocrystallite parameters can be obtained using magnetron sputtering with discharge current of 0,4 A and oxygen content in a target up to 8 at.%. Application of TiB₂-based nanocrystal films as antidiffusion layers in contacts to wide-gap semiconductors makes it possible to raise heat stability of devices based on such semiconductors.

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