Effect of CdTe layer thickness on multimode optical thermometry for cryogenic temperatures

Traditional contact thermometry faces a lot of challenges in the cryogenic temperature range. Remote temperature sensing techniques, especially optical thermometry, offering fast response, high spatial and temperature resolution could be a promising solution. Here, ZnTe/CdTe nanostructures with different CdTe layer thicknesses were tested as multimode temperature sensors in the cryogenic range of 20–70 K. The temperature reading was provided by monitoring LIR, spectral position, bandwidth, and energy gap, which enhances the reliability of thermometry. The effect of CdTe layer thickness was studied in terms of thermometric performances. The best thermal sensitivity of 9.8 % K⁻¹@20K was achieved using the energy gap, while the minimum temperature resolution of 0.2 K@20K was obtained using the spectral position. Despite the better thermometric performance of the 1 ML sample, the 2 ML sample offers a wider choice of temperature-sensitive parameters for optical thermometry, making it more versatile.