Optical temperature measurement method for glowing microcomponents

M. Shpak, P. Kärhä, M. Ojanen, E. Ikonen, M. Heinonen

Research output: Contribution to journalArticleScientificpeer-review


A measurement method and measurement results for the temperature of miniature microbridge emitters integrated on silicon are presented. First, the extinction coefficient of highly doped silicon was measured at high temperatures: a piece of a silicon-on-insulator wafer was heated to several temperatures in a high-temperature furnace, and the emitted spectra were measured using a spectroradiometer with focusing optics. The optical behavior of the sample was modeled with Fresnel equations. The extinction coefficient of silicon was obtained from the model, because other optical properties, the dimensions, and the temperature of the structure were known. An emissivity model was then developed and adapted for the microbridge with the known extinction coefficient values, which allows the temperature to be determined from the measured spectrum. We can now measure optically the temperatures of the microbridges of dimensions 400 × 25 × 4 μm 3 in the temperature range 600 °C to 1200 °C with an uncertainty of 100°C.

Original languageEnglish
Pages (from-to)1762-1770
Number of pages9
JournalInternational Journal of Thermophysics
Issue number8-9
Publication statusPublished - 2010
MoE publication typeA1 Journal article-refereed


  • Emissivity
  • High temperatures
  • Microbridge
  • Refractive index
  • Silicon

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