Double side polished vs. single side polished sapphire substrates
Laytek’s Application note 28 describes the effects of double side polished sapphire wafers versus
single side polished wafers to the true temperature measurement of LayTec’s in situ sensors.

The study was performed on two identical Gallium Nitride (GaN) buffer growth runs monitoring the effect of the Sapphire substrate backside polishing on the true temperature signal using the Laytec IR Pyrometer. The only difference in the growth parameter was the substrate type: wafer #1 was a sapphire 2” wafer with a rough backside, and wafer #2 a double side polished 2”sapphire wafer.

To quote one interesting comment:

“The effect of the double side polished sapphire on the reflectance signal is a certain increase in the average reflectance (the back side reflectance contribution) and a relative shrinking of the Fabry-Perot oscillation amplitude. All these effects could be perfectly modelled by the LayTec’s AnalysR
software”

You can view the complete Applications note, TT measurements: double side polished vs. single side polished sapphire substrates, or download it from the Laytec website by clicking here (PDF - 122 Kb).

pdf - 122 kb

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