Research On CIS Fabrication Of LiTaO₃ Single Crystal Thin Film And Pyroelectric Infrared Detector

LiTaO₃ infrared detector has applied in target detection,gas monitoring,security and smart home because of its advantages of uncooling,low power consumption,wide response wavelength range and stability.However,two serious problems make LiTaO₃pyroelectric infrared detector difficult to meet the high-frequency application need and miniaturization development trend.First,it is hard to prepare high-quality LiTaO₃ single crystal film by traditional method to improve detection peak frequency.Second,traditional structure contains optical filter which cannot be integrated with the pyroelectric material.Therefore,this dissertation carried out a LiTaO₃ single crystal infrared detector based on crystal ion slicing and metamaterial perfect absorber,aims to use high-quality LiTaO₃ single crystal film to increase detection peak frequency and use metamaterial perfect absorber to replace optical filter,laying the foundation for further reducing the weight and volume of the detector.The main work are as follows:(1)Nondestructive measurements have been used to study the ion fluence effect on wafer structure and determine the key fabrication parameters of single crystal film.Usually,RBS,SEM,TEM were used to characterize the property change of wafer during implantation.But these methods will bring irreversible damage to implanted wafer.To investigate the property of LiTaO₃ wafer with different implantation fluences,visible spectroscopy and electron paramagnetic resonance were used to study the effect of H-ion fluence on transmittance,infrared spectroscopy was used to analyze the chemical state of H-ion,Raman scattering and X-ray diffraction were used to measure the stress evolution of wafer,and summarized the relation between fluence and slicing temperature and time by thermal blistering experiment.The results show that the H-ion mainly occupied the interstitial proton position in the O?O bond,oxygen vacancies created by implantation caused the decrease in visible light transmittance of wafer.The increase of interstitial proton and oxygen vacancy increased the wafer stress,reduced the blistering activation energy and promoted film slicing.(2)LiTaO₃ single crystal films have been treated by rapid thermal annealing to release the stress and recover the crystal damage,and infrared detector has been fabricated using LiTaO₃ single crystal films to verify its pyroelectric properties.1?m thick LiTaO₃single crystal film was prepared by hydrophilic bonding,and this film was treated by rapid thermal annealing.Its surface microstructure was characterized by AFM,crystal structure was measured by XRD and chemical composition variation was studied by XPS.The results show that,annealing treatment caused recrystallization on film surface,the compressive stress decreased from 0.83%to 0.39%,damage of the film was repaired to a certain extent,FWHM of rocking curve decreased from 0.04°to 0.03°,and no chemical composition change observed.The detectivity of LiTaO₃ single crystal film detector reached 3.3×10⁸cm Hz^1/2/W at 50.3Hz,which verified the infrared detection performance of LiTaO₃ single crystal film.(3)Metamaterial perfect absorber was used as infrared absorption layer to achieve the wavelength-selective function of pyroelectric infrared detector.To solve the problem that traditional absorption layer cannot selectively absorb radiation with different wavelength,infrared detectors usually use optical filter which will increase the volume and limit the integration of detector.This dissertation proposed using metamaterial perfect absorber as absorption layer,based by surface plasmon polariton to absorb radiation and control absorption wavelength by changing the structure parameters.Designed and prepared cross metamaterial perfect absorber realized the selective absorption of radiation with different wavelength by exciting surface plasmon polariton at the metal dielectric interface,and its mid-infrared absorption rate is higher than 90%.The integration infrared detector of metamaterial absorption layer and pyroelectric material was realized based on LiTaO₃ bulk,and its detectivity reached 3.24×10⁷cm Hz^1/2/W,the detection peak frequency is 26.3Hz.A new metamaterial perfect absorber was designed to increase angle absorption stability,and a film pyroelectric infrared detector with wavelength-selective function was prepared.The experiments show that this detector has selective absorption function of 4.04?m wavelength infrared light,maximum detectivity 1.7×10⁸cm Hz^1/2/W,stable response at incidence angle range of 0?50°,and detection peak frequency of80.3Hz.These results verified the metamaterial perfect absorber single crystal thin film infrared detector has good wavelength-selective function,high infrared detectivity,and excellent high-frequency response characteristics.