Investigation of cerium oxide thin film thickness using THz spectroscopy for non-destructive measurement

Through time of non-destructive measurement of individual layer of materials or paint layers at nano-scale, non-contact terahertz technique is a very good approach. In this research work, the cerium oxide (CeO2) thin film is deposited on sapphire (c-Al2O3) substrate having thickness of 430 µm by using RF magnetron sputtering technique. A terahertz pulses incident on the CeO2 film, layer of CeO2 interface with substrate. Some amount of incident pulse transmits and rest will reflect with respect to transmission mode and reflection mode, respectively. In the reflection mode, the time elapsed between the arrival and departure of cerium oxide layer is directly proportional to the thickness of the layer as a function of wavelength. The thickness of CeO2 is measured about 35.83 µm using terahertz spectroscopy. This study shows that terahertz spectroscopy is an experimental approach and possible to measure thickness of thin film for non-destructive measurement.