Evaluation of Mid-Infrared Response Characteristics Based on Variations in Platinum Addition Concentration in Radio Frequency Sputtering-Deposited Magnetite Thin Films

Magnetite (Fe₃O₄) possesses a 0.1 eV bandgap and exhibits responsivity to mid-infrared radiation, making it a promising candidate to replace existing electromagnetic wave detector materials. Optimization of platinum (Pt) addition concentration to Fe₃O₄ thin films is expected to enhance sensitivity by facilitating the capture of electrons generated by electromagnetic radiation. In this study, to identify the optimal Pt addition concentration for enhancing the mid-infrared detection sensitivity of Fe₃O₄ thin films, the response under mid-infrared irradiation was evaluated using seven samples with Pt addition concentrations ranging from 0 at.% to 9.4 at.%. Plotting the peak intensity based on the mid-infrared response revealed no correlation between Pt concentration and peak intensity. The sample with the highest peak intensity was the one with the highest Pt concentration in this study (9.4 at.%), exhibiting an average peak intensity of 0.014. The signal-to-noise (S/N) ratio, calculated based on the peak intensity of the response and the effective value of the noise, was the highest for the sample with a Pt addition concentration of 1.6 at.%, which had an electrical resistivity of 1.4 × 10⁴ µΩ cm. This confirmed that this condition represents the optimal Pt addition amount under the conditions adjusted in this study.