Research On 3-5 ?m Infrared Transparent Conductive Oxide Film

Infrared gas detection system is used to detect combustible gas under the mine due to its high test accuracy and fast speed.Dust and water vapor under the mine seriously interfere with the sensitivity and accuracy of gas detection.The transparent conductive film can remove optics due to its unique photoelectric performance Dust and water vapor on components.However,at present,the transparent conductive film is only transparent in the visible light band and cannot be applied to the 3⁵?m atmospheric window band commonly used for infrared gas detection.Therefore,it is of great significance to study the transparent conductive film suitable for the 3⁵?m band to improve the anti-interference ability of the detection system.In this paper,three infrared transparent conductive films were prepared on quartz,sapphire,and zinc selenide substrates by ion beam assisted thermal evaporation and RF magnetron sputtering.They are In₂O₃,hafnium-doped indium oxide?IHfO?,and hafnium-doped zinc oxide?HZO?.The effects of experimental parameters on the crystal structure and photoelectric properties of thin films were studied.First,the ion beam assisted thermal evaporation method was used to prepare the In₂O₃ film,and the effects of oxygen flow rate and annealing temperature on the crystal structure and photoelectric properties of the In₂O₃ film were investigated.The results show that the In₂O₃ film has a preferred orientation in the?222?direction,and an increase in oxygen flow rate is conducive to film crystallization.When the oxygen flow rate is 0.6 sccm,transmission of the In₂O₃ film at 3?m is about 78%,and the resistivity is 3E-2?·cm.As the annealing temperature gradually increases,the film grain size increases.After annealing at 300?,the transmittance of In₂O₃ film at 3?m is greater than 90%,and the resistivity is about 8E-2?·cm.Secondly,a IHfO thin film was prepared by RF magnetron sputtering.The effects of oxygen flow rate and annealing temperature on the crystal structure and photoelectric properties of the IHfO thin film were investigated.When the doping concentration is increased from 1wt.%to 4wt.%,The preferred orientation of the IHfO film gradually changes from?222?to?400?direction.The test results show that most of the Hf ions in the IHfO film replace the position of In ions in the crystal lattice.When the doping concentration is 2wt.%,The average transmittance of IHfO film in the infrared band of3⁵?m is about 85%.As the doping concentration increases,the transmittance of the IHfO thin film decreases and the resistivity increases.When the doping concentration is 2wt.%,The resistivity of the IHfO thin film reaches the minimum value,which is about 5E-3?·cm.When the substrate temperature is 350?,the average transmittance of the IHfO film prepared in the infrared band of 3⁵?m is about 72%,and the resistivity is about 1.2E-3?·cm.Finally,a HZO film was prepared by magnetron sputtering,and the effects of sputtering power and self-buffer layer on the crystal structure and photoelectric properties of the HZO film were investigated.The results showed that increasing the sputtering power from 60W to 80W did not change the preferred orientation of the HZO thin film.The performance of the HZO thin film prepared at the sputtering power of70W is optimal.At this time,the average transmittance of the thin film in the infrared band of 3⁵?m is about 68%,and the resistivity is about 3.6E-4?·cm.The self-buffer layer has the characteristics of crystal orientation induction and improved surface morphology of the HZO film.The average transmittance of the HZO film with the self-buffer layer in the infrared band of 3⁵?m is increased by about 2%compared with the ordinary HZO film,the mobility increased by 2.1 cm²V^-1s^-1,and the resistivity decreased by about 0.21?·cm.