Preparation And Device Research Of Heat Flux Sensitive Thin Film Materials

As science and technology move forward faster and faster,more and more attention has been paid to the measurement of heat flux.Compared with the traditional heat flux meters,the atomic layer thermopile（ALTP）heat flux sensor based on transverse Seebeck effect not only has a simple structure,but also has some advantages in sensitivity and response speed.However,at present there is still no large-scale commercial application,because the performance of the sensor needs to be further improved and the requirement of integrated miniaturization based on the current scientific and technological development also needs to be solved.Therefore,it is necessary to further develop a miniaturized ALTP heat flux sensor with high sensitivity on the basis of the existing technology,which can be used for high frequency response heat flux measurement.In this thsis,the preparation technology of YBa₂Cu₃O_7-（?）（YBCO）and La_xCa_1-xMn O₃（LCMO）thermoelectric thin films was studied.An ALTP heat flux sensor with multi-line that amplifies the test signals was designed and fabricated,and the test and calibration were carried out.The specific work was as follows:1.The preparation technology of heat flux sensitive film was studied.YBCO thin films were prepared by magnetron sputtering,all of which were c-axis oblique epitaxial and the surface of the film was smooth and without holes.The specific tilt angle of the films was 12.13°by TEM measurement.LCMO thin films were prepared by the MOCVD system built in the laboratory,and the preparation process has been explored.2.The fabrication technology of heat flux sensor was studied.Firstly,multiple pieces heat flux sensors with signle YBCO line were prepared simultaneously using a metal mask,and the test results show that the sensor prepared by this method had good repeatability and consistency.At the same time,in order to increase the sensitivity of the sensor,a multi-line structure was designed and heat flux sensors with four YBCO lines in series were fabricated by wet etching.In addition,in order to further integrate more thermopile lines,we also focused on the lithographic graphic transfer technology,which lays a foundation for the manufacture of heat flux sensors with better performance.3.The resistance test and laser induced voltage（LITV）test of the heat flux sensitive film were carried out respectively.The properties of YBCO films had degenerated when the temperature was above 600℃,while LCMO films still had good electrical conductivity at high temperature of 1100℃.Laser mesurement shows that the relationship between the thickness of YBCO film and the peak value of response signal coincides with the theory of LITV response,and there is an optimal film thickness.The thinner the film thickness of YBCO is,the shorter the LITV response time is,and the response time of 100nm film thickness sensor was only 34ns,which provides an idea for the design of high frequency heat flux sensor.The prepared LCMO film had obvious response signal under laser irradiation,and the response time was on the microsecond scale.The devices were calibrated by comparative calibration method:the size of the sensitive element of heat flux sensor with single YBCO line was 3mm（18）0.4mm and the film thickness was 250 nm.The sensitivity was 82.4(1/(（2/（88）²）,and the response time was less than 0.2s.The size of each line of the heat flux sensor with four YBCO lines in series was 8mm（18）0.3mm and the film thickness was 1m.The sensitivity was1107.9(1/(（2/（88）²）which was significantly improved.