Phase-separation phenomenon of NiGePt alloy on n-Ge by microwave annealing

Chung Chun Hsu, Kun Lin Lin, Wei Chun Chi, Chen Han Chou, Guang Li Luo, Yao Jen Lee, Chao-Hsin Chien*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


During the formation of distinct bilayer NiGePt alloy, a phase-separation phenomenon was observed using microwave annealing and structural engineering. The microstructures of bilayer NiGePt [PtGe(Ni)–NiGe(Pt)] alloys fabricated with 10-nm Ni and various thicknesses of Pt (5, 10, and 15 nm) were characterized. Within the same thermal budget as microwave annealing, the diffusion of Ni exhibited stronger alloy formation ability with Ge and drilled through the Pt layer without resistance. The higher diffusivity of Ni atoms dominated the diffusion of Ni through the Pt layer to form a stable crystalline layer, NiGe(Pt). Ge diffused outwardly toward the Pt layer to form a PtGe(Ni) layer. This special phenomenon of bilayer alloy formation was elucidated using nanobeam electron diffraction by transmission electron microscopy in conjunction with energy-dispersive spectrometry. Comparing the differences in metal alloys between microwave and rapid thermal annealing, microwave annealing formed a bilayer alloy more apparently than rapid thermal annealing. The results and electrical characteristics indicated that a thicker Pt layer for forming a bilayer NiGePt alloy with alloy separation could also effectively improve the leakage current of NiGePt [PtGe(Ni)– NiGe(Pt)]/n-Ge Schottky junctions.

Original languageEnglish
Pages (from-to)262-267
Number of pages6
JournalJournal of Alloys and Compounds
StatePublished - 30 Apr 2018


  • Microwave-activated annealing
  • NiGePt
  • Phase-separation alloy
  • Schottky junction


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