Quasi continuous wave laser sintering of Si-Ge nanoparticles for thermoelectrics

Kai Xie, Kelsey Mork, Jacob T. Held, K. Andre Mkhoyan, Uwe Kortshagen, Mool C. Gupta

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Silicon-germanium is an important thermoelectric material for high temperature applications. In this study, thin films composed of SiGe nanoparticles were synthesized in a plasma reactor and sintered by a millisecond pulse width, quasi continuous wave, near infrared laser of wavelength 1070 nm. We demonstrate that laser sintered SiGe thin films have high electrical and low thermal conductivity, dependent on the surface morphology and dopant concentration. Substrate wetting of laser heating induced molten SiGe was found to play an important role in the final surface morphology of the films. Interconnected percolation structures, formed when proper substrate wetting occurs, were found to be more conductive than the balling structure that formed with insufficient wetting. Laser power was adjusted to maximize dopant reactivation while still minimizing dopant evaporation. After optimizing laser sintering process parameters, the best electrical conductivity, thermal conductivity, and Seebeck coefficient were found to be 70.42 S/cm, 0.84 W/m K, and 133.7 μV/K, respectively. We demonstrate that laser sintered SiGe thin films have low thermal conductivity while maintaining good electrical conductivity for high temperature thermoelectric applications.

Original languageEnglish (US)
Article number094301
JournalJournal of Applied Physics
Volume123
Issue number9
DOIs
StatePublished - Mar 7 2018

How much support was provided by MRSEC?

  • Partial

Reporting period for MRSEC

  • Period 4

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