Porosity-tuned thermal conductivity in thermoelectric Al-doped ZnO thin films grown by mist-chemical vapor deposition

Shrikant Saini, Paolo Mele*, Takafumi Oyake, Junichiro Shiomi, Janne Petteri Niemelä, Maarit Karppinen, Koji Miyazaki, Chaoyang Li, Toshiyuki Kawaharamura, Ataru Ichinose, Leopoldo Molina-Luna

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)

Abstract

The potential of thermoelectric thin films lies in wide range of applications from micro-energy harvesting to the sensors. For this, it is essential to have high power factor and ultra-low thermal conductivity which have been reported in thin films produced by expensive vacuum techniques. However, for practical applications, it is essential to use inexpensive technique to grow thin film in large area. In this direction, we report the use of mist-chemical vapor deposition (CVD) technique to develop oxide thin films for thermoelectric application. We grow c-axis oriented nano-porous thin films of 2% Al-doped ZnO (AZO). These nano-porous films have enhance phonon scattering which results in the depression of thermal conductivity (κ) while maintaining similar order of magnitude of power factor as reported in dense films prepared by vacuum techniques. For example, κ300K decreases from 6.5 W/m.K for dense thin film (porosity = 7.9%) grown by pulsed laser deposition to 5.54 W/m.K for porous film (porosity = 24.2%) grown by mist-CVD while maintaining the power factor of similar order of magnitude for AZO film deposited on SrTiO3. The depression of thermal conductivity in porous films may lead to higher figure of merit which is promising for practical applications of thermoelectric oxide films.

Original languageEnglish
Pages (from-to)180-185
Number of pages6
JournalThin Solid Films
Volume685
Early online date11 Jun 2019
DOIs
Publication statusPublished - 1 Sep 2019
MoE publication typeA1 Journal article-refereed

Keywords

  • Mist-chemical vapor deposition
  • Oxides
  • Porosity
  • Thermoelectric effect
  • Thin film
  • Zinc oxide

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