Electroless Co-P diffusion barrier for n-PbTe thermoelectric material

Hsien Chien Hsieh, Chun Hsien Wang, Wen Chih Lin, Subhendu Chakroborty, Tse Hsiao Lee, Hsu Shen Chu, Albert T. Wu

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

This work describes an in-depth study on the electroless deposition of Co–P via the addition of a reductant to a solution on a roughened, sensitized, and activated n-PbTe thermoelectric substrate. The Co–P layer facilitates the bonding of the thermoelectric module with the solder paste and serves as a diffusion barrier that prevents severe interaction between n-PbTe and Cu or Ni electrodes. Without this layer, a eutectic reaction produces molten PbTe because of the fast diffusion of Cu; moreover, a large Cu2Te phase is formed, resulting in the depletion of Cu from the Cu electrode. In addition, Pb and Te diffuse along the grain boundaries of the Ni electrode in the Ni/n-PbTe joint. Cross-sectional images and elemental analysis results show that the Co–P layer could efficiently inhibit interdiffusion in the Ni/n-PbTe and Cu/n-PbTe joints. These results provide new insights for developing PbTe thermoelectric devices using Ni or Cu electrodes with high reliability at working temperatures.

Original languageEnglish
Pages (from-to)1023-1029
Number of pages7
JournalJournal of Alloys and Compounds
Volume728
DOIs
StatePublished - 2017

Keywords

  • Diffusion
  • Phase transitions
  • Solid state reaction
  • Thermoelectric materials

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