Noncontact measurement of the thermal diffusivity of IR semi-transparent and semiconducting n-CdMgSe mixed crystals by means of the photothermal radiometry

• The measurement of the thermal diffusivity of IR semi-transparent crystals was performed by means of the PTR.
• The thermal diffusivities were estimated using the simple well-known formula for thermally thick samples.
• The three layer model of the PTR signal was developed.
• The influence of thin, blocking IR radiation, layers on the PTR phase was discussed.

In this paper we present results of noncontact measurements of the thermal diffusivity of infrared semi-transparent n-CdMgSe mixed semiconductor crystals by means of the photothermal radiometry (PTR) in a transmission configuration. In order to overcome an influence of the infrared semi-transparency and plasma waves on the PTR signal from n-CdMgSe mixed crystals the samples were covered by thin aluminum foils on both sides. The thermal diffusivities of n-CdMgSe mixed crystals were estimated from PTR phase frequency characteristics using a well-known formula. It was found that the obtained results are underestimated in comparison to thermal diffusivities estimated from the PPE (photopyro-electric) measurements. A three layer model of a PTR signal was applied in order to estimate an error in determination of the thermal diffusivity of a sample caused by aluminum foils.