Investigation of Heat Transfer of Bulk and Thin-Film PbInTe Samples by the Method of Dynamic Gratings

Abstract

Measurements of the thermal diffusivity of thin and bulk indium-doped lead telluride have been taken using a modified method of dynamic gratings. Thermal gratings were recorded by a 20 ns pulsed laser radiation at a wave length of 532 nm. Dynamic gratings were recorded by a 635 nm continuous laser radiation. The analysis of the diffraction signal kinetics made it possible to determine the life-time of thermal gratings recorded in the investigated samples. It is shown that the use of an additional homodyne field coherent with respect to the diffraction signal field makes it possible to enhance and filter off the selected information component. Based on registered kinetic dependences of the diffracted signal intensity, the thermal diffusivity of bulk and thin film indium-doped lead telluride samples was determined. It has been established that for a micron-thick film, the thermal diffusivity is ten percent lower than for a bulk sample. An investigation has been made into the dependence of the heat transfer in the said samples on their temperature and it has been shown that the rise in the samples′ temperature in the range from 40 to 95°C results in a 20-percent decrease of their thermal diffusivity.