Preparation Process Opimazation And Porperties Of CuAlO₂ Films Prepared By RF Magnetron Sputtering

CuAlO2 is a kind of semiconductor materials with excellent electrical properties and optical, so it has been widely used in many fields of photoelectic. The very low conductivity of CuAlO2 film compared to n-type TCO limits application and development of transparent electronics. Therefore, how to improve the conductivity of CuAlO2 has become the research focus in recent years. In this dissertation, CuAlO2 film was prepared by RF magnetron sputtering method on the quartz glass substrate. X-ray diffraction, scanning electron microscope and ultraviolet-visible spectrophotometer were used to analysis the microstructure, surface topography, and visible transmission spectral. The effects of the ratio of Ar to O2, substrate temperature and annealing temperature films were investigated of DSC and specific heat. The main results are as follow:1) Under certain condition that the oxygen argon ratio is 1:4, the sputtering pressure was 1 Pa, the sputtering power was 120W, the annealing temperature was 900℃, the annealing time was 2h, Substrate temperature have an impact of all performance. When the Substrate temperature below 300 ℃, the diffraction peak is very low, grain boundary is no obvious. When the Substrate temperature is 400 ℃ and 500℃,the(006)、(101) etc diffraction peaks appear. The size of grain is very uniform, the films become smooth and compact. But when the temperature is 500 ℃, the film starts to haircuts; average transmission rate of all film is very high, the highest up to 79.8%. And the absorption edge of the films moves toward the short wavelength2) Under certain condition that the substrae temperature is 400℃, the sputtering pressure is 1Pa, the sputtering power is 120W, the annealing temperature is 900 ℃, the annealing time is 2h, With the increase of oxygen content, the (006)、 (101)and (012)diffraction peak are strengthened gradually; The size of grain first increases and then decreases; average transmission rate is obtained. When oxygen content is higher than 40%, the impurity phases CuO appears.3) Under certain condition that the substrate temperature is 400 ℃, the oxygen argon ratio is 1:4, the sputtering power is 120 W, the annealing temperature is 900℃, the annealing time is 2h, the sputtering pressure is 1～4Pa, With the change of working pressure, the (101)and (014)diffraction peaks appear.; The size of grain first increases and then decreases; If the working pressure is too high, the film starts to haircuts; average transmission rate of all film is very high, When the working pressure is 2 Pa, the average transmission rate is 74.6%.4) Under certain condition that the substrate temperature is 400℃, the oxygen argon ratio is 1:4, the sputtering pressure is 2 Pa, the sputtering power is 120 W, With the increase of annealing temperature from 800℃ to 900℃, the (101) diffraction peak is strengthened gradually. But when the annealing temperature is 950℃, the film began to fall off. the average transmission rate of the film is the biggest, which is 74.7%. The optical band gap of the film is 3.60 eV5) Under certain condition that the substrate temperature is 400 ℃, the oxygen argon ratio is 1:4, the sputtering pressure is 2 Pa, the sputtering power is 120W. When the annealing time is 2 h, the (101) diffraction peak is the strongest With the increase of annealing time, the diffraction peak gradually disappears:the average transmission rate of the film did not change much, all of them are around 73%.6) In summary, the optimal process condition for the preparation of CuAlO2 thin films are:the oxygen argon ratio is 1:4, the substrae temperature is 400 ℃, the sputtering pressure is 2 Pa, the annealing temperature is 900℃,the annealing time wis 2 h.7) Thermal stability have not been affected with the change of the ratio of Ar to O2 and substrate temperature:Under nitrogen atmosphere, any peak did not appear of the DSC curve, when the temperature below 900℃; When the temperature over 900 ℃, the peak appear; The heat capacity increase slowly, when the film temperature between 50 and 298℃. The curve of the heat capacity is Continuous and smooth, no exceptions occur.8) Thermal stability of the films have been affected with the change of annealing temperature:When the annealing temperature is 1000℃, any peak did not appear in the DSC curve between 25 and 1050℃. When the annealing temperature is 900℃, any peak did not appear in the DSC curve within the temperature below 900℃, and the peak appears within the temperature over 900℃.