Formation of ultra-low resistance contact with nickel stanogermanide/heavily doped n+-Ge1−xSnx structure

Abstract

We examined the formation of Ni(Ge1−xSnx)/n+-Ge1−xSnx contacts with Sb- and P-doped Ge1−xSnx 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 Ge1−xSnx layer after Ni stanogermanidation, while the Sn content slightly decreased. The contact resistivity of Ni(Ge1−xSnx)/Sb-doped Ge1−xSnx 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 10−9 Ω cm2 was obtained with the Ni(Ge1−xSnx)/Sb-doped Ge0.935Sn0.065 sample with an electron concentration of 1.8 × 1020 cm−3.