The Ni-stanogermanides were formed via an interfacial reaction between Ni film and a Ge
1−xSn
x (x = 0.083) epilayer grown on a Si substrate driven by thermal treatment, and their microstructural and chemical features were investigated as a function of a
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The Ni-stanogermanides were formed via an interfacial reaction between Ni film and a Ge
1−xSn
x (x = 0.083) epilayer grown on a Si substrate driven by thermal treatment, and their microstructural and chemical features were investigated as a function of a rapid thermal annealing (RTA) temperature. The Ni
3(Ge
1−xSn
x) phase was formed at the RTA temperature of 300 °C, above which Ni(Ge
1−xSn
x) was the only phase formed. The fairly uniform Ni(Ge
1−xSn
x) film was formed without unreactive Ni remaining after annealing at 400 °C. However, the Ni(Ge
1−xSn
x) film formed at 500 °C exhibited large surface and interface roughening, followed by the formation of Ni(Ge
1−xSn
x) islands eventually at 600 °C. The Sn concentration in Ni(Ge
1−xSn
x) gradually decreased with increasing RTA temperature, implying the enhancement of Sn out-diffusion from Ni(Ge
1−xSn
x) grains during the Ni-stanogermanidation process at higher temperature. The out-diffused Sn atoms were accumulated on the surface of Ni(Ge
1−xSn
x), which could be associated with the low melting temperature of Sn. On the other hand, the out-diffusion of Sn atoms from Ni(Ge
1−xSn
x) along its interface was dominant during the Ni/Ge
1−xSn
x interfacial reaction, which could be responsible for the segregation of metallic Sn grains that were spatially confined near the edge of Ni(Ge
1−xSn
x) islands.
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