Thickness effect and etching implement of silicon substrate of LiTaO 3 thin film infrared detector

Abstract

The pyroelectric LiTaO₃ thin film has low heat capacity, low thermal loss, high pyroelectric response and high possibility to make infrared detector, so the LiTaO₃ thin film infrared detector preparation is considered in this paper. During the fabricated experiments, the silicon substrate thickness effect on performance of the LiTaO₃ thin film device is very large, and therefore it has been theoretically investigated by using the MATLAB software and by employing one-dimensional heat conduction equation. The simulation results show the thinner the silicon substrate, the less the thermal loss by conduction, and thus, the higher the pyroelectric response of the LiTaO₃ thin film device. To verify the theoretical analysis, the LiTaO₃ thin film device deposited on the Pt/Ti/SiN_x/SiO₂/Si(100) substrate with different silicon substrate thickness are fabricated and the etching process of the silicon substrate have been discussed in details. The experimental results of the current responsivitiy and the specific detectivity of the LiTaO₃ thin film device agree with the theoretical analysis. The theoretically and experimental results are together determined that, thoroughly etched-off the silicon substrate is the best method to reduce thermal loss and improve the property of the LiTaO₃ thin film device.