Formation of ultra-low resistance contact with nickel stanogermanide/heavily doped <i>n</i> ⁺ -Ge _{1− <i>x</i>} Sn _<i>x</i> structure

<jats:title>Abstract</jats:title> <jats:p> We examined the formation of Ni(Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> )/ <jats:italic>n</jats:italic> <jats:sup>+</jats:sup> -Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> contacts with Sb- and P-doped Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> epitaxial layers with various electron concentrations and investigated the crystalline structure and contact resistivity. The fully maintained strain and no serious degradation of the crystallinity were confirmed in the Sb-doped Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> layer after Ni stanogermanidation, while the Sn content slightly decreased. The contact resistivity of Ni(Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> )/Sb-doped Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> interface achieved a value lower than the P-doped samples, in spite of high Sn contents with a Ni germanidation temperature of 350 °C. The ultra-low contact resistivity as low as 10 <jats:sup>−9</jats:sup> Ω cm <jats:sup>2</jats:sup> was obtained with the Ni(Ge <jats:sub> 1− <jats:italic>x</jats:italic> </jats:sub> Sn <jats:sub> <jats:italic>x</jats:italic> </jats:sub> )/Sb-doped Ge <jats:sub>0.935</jats:sub> Sn <jats:sub>0.065</jats:sub> sample with an electron concentration of 1.8 × 10 <jats:sup>20</jats:sup> cm <jats:sup>−3</jats:sup> . </jats:p>