Research On Fabrication And Infrared Radiation Properties Of HfB₂ Thin Films

Hafnium boride(HfB₂),as an ultra-high temperature conductive ceramic material,has excellent properties such as high melting point,high electrical conductivity,and stable chemical properties,and is expected to be used in the field of infrared stealth.At present,the research on HfB₂ at home and abroad mainly focuses on the properties of high temperature resistance,oxidation resistance,thermal shock resistance,corrosion resistance,ablation resistance,etc.,but less research in the field of infrared stealth materials.This thesis takes HfB₂ film as the research object,and carries out related research work on the preparation process,electrical conductivity and infrared radiation characteristics of the film.The research contents are as follows:1.Based on the first-principles calculations of HfB₂,combined with the Drude-Lorentz dispersion model,the infrared low emissivity characteristics of HfB₂ materials were explored.The electronic structure and optical properties of HfB₂ crystals were simulated using Materials Studio software.The energy band structure and density of states of HfB₂ are calculated to show that HfB₂ has metal-like conductivity;the complex dielectric function,complex refractive index and reflection function of HfB₂ crystal in(100)and(001)directions are calculated and found HfB₂ crystals exhibit strong reflective properties and anisotropy.Combined with the Drude-Lorentz dispersion model,the plasma frequency and damping factor of HfB₂ materials are regulated in the infrared low energy region,and it is found that increasing the free electron concentration and reducing electron scattering can reduce the infrared emissivity of HfB₂ materials.2.The effects of sputtering power and film thickness on the infrared radiation properties of HfB₂ films were studied.By adjusting the resistivity of the HfB₂ film,the emissivity of the HfB₂ film can be reduced.The average emissivity of the prepared HfB₂film is 0.15,showing a relatively excellent low emissivity characteristic.3.The effect of Si substrate roughness on the infrared radiation properties of HfB₂films with different thicknesses was investigated.It was found that with the increase of roughness,the specular reflectance of HfB₂ films decreased from 0.85 to 0.36(?=10.6?m)while maintaining low infrared emissivity(<0.28).It achieves low infrared emission and low infrared specular reflection,and is expected to be applied to infrared/laser compatible stealth.