| Infrared detectors are widely used in the military and commercial fields,such as infrared imaging,infrared guidance,high-speed detection and so on.Pyroelectric infrared detectors have great application and research value compared with other types of infrared detector because of their advantages such as no refrigeration,no selectivity of absorption spectra,low cost and simple structure of the devices.For high-speed detection applications,pyroelectric infrared detectors should have a high detectivity and signal-to-noise ratio in order to detect the target.Aiming at the application,on the one hand,it is necessary to research the pyroelectric thin film material in order to improve the material properties;on the other hand,it is also necessary to carry out the structural design to reduce the heat loss and improve the response frequency.Development of high quality,low cost pyroelectric thin film material preparation technology and design miniaturization,high performance,non-refrigeration detector structure is the current research direction of the pyroelectric infrared detector.The Crystal Ion Slicing?CIS?technology can produce sub-micron-thick high-quality single-crystal pyroelectric thin film materials,which have the advantages of controllable film thickness and good film quality.In this thesis,the structure design of single-crystal LiTaO3 thin film and infrared detector was prepared by CIS.The research work includes 3 parts.1.Research on the preparation of LiTaO3 film based on CIS.Firstly,ion implantation was simulated by SRIM,and the optimal implantation energy and dose were selected.Then,the annealing temperature curve and parameters of process was studied.The electrical properties such as leakage current,dielectric properties,and pyroelectric coefficient were tested.At the 1k frequency,the dielectric constant?r is 83,the dielectric loss tan?is 65,the pyroelectric coefficient p is 2.13×10-8 C/cm2·K-1,and the detection merit Fd is 6.25×10-3pa-1/2.2.Single-crystal LiTaO3 thin film infrared detector was simulated.Firstly,we have designed detector structures,including BCB glue bonding layer,SiO2 bonding layer,BCB glue and SiO2,and the cavity layer structures.The difference of the average temperature change rate under the film is compared.For the SiO2 bonding layer device,the frequency response simulation was carried out,and the relationship between the film temperature change rate AP-P and the radiation modulation frequency f was obtained.By loading the step function heat source,the thermal time constant of the detector was 28.2 ms;After loading the pulse heat source,the temperature rise of the detector and the change of the pyroelectric current are obtained.3.The preparation and testing of infrared detectors were carried out.After the surface of Ni0.8Cr0.2 alloy is treated by laser scribing process,the infrared absorption can reach more than 50%.The response voltage VP-P and noise voltage VN of the thin film detector were tested,and the device characteristics such as the device voltage response rate Rv and the specific detection rate D*were calculated.When the modulation frequency f=0.2Hz,the noise is greater than 100?V/?Hz;when the modulation frequency f=300Hz,the noise is equal to 2?V/?Hz;at f=100Hz,the voltage response rate Rv of the detector reaches the maximum,about 5×103V/W;when the modulation frequency f>100 Hz,the specific detection rate of the thin film infrared detector is D*>5.0×108cm·Hz1/2W-1. |
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