Effect Of In-situ Annealing On The Properties Of Mg₂Si Thin Films Prepared By Magnetron Sputtering

Mg₂Si is an environment-friendly semiconductor material with important potential for development in optoelectronic devices.In this paper,Mg₂Si thin films were prepared on soda-lime glass substrates by in-situ annealing using magnetron sputtering.The influences of in-situ annealing temperature and time on the crystal structure,the surface morphology and the square resistance of Mg₂Si thin films were studied.After determining the optimal heat treatment parameters for in-situ annealing and the order of Si and Mg sputtering exchanged,the crystal structure and the surface morphology?CSSM?of Mg₂Si thin films were studied further.Then,the effects of different in-situ annealing temperature and different film thicknesses on the CSSM of Mg₂Si thin films were studied under the multilayer film sputtering.First,Mg₂Si thin films were prepared by single-layer sputtering.The Si and Mg films on a soda-lime glass substrate were performed by magnetron sputtering for 25mins and 18 mins respectively at room temperature.And Mg₂Si thin films were prepared by in-situ annealing at 400-600°C for 3-5 h.The CSSM of thin films were characterized by X-ray diffractometer and scanning electron microscope.The results show that the single-phase Mg₂Si films can be successfully prepared by annealing at each annealing temperature.And the Mg₂Si?220?diffraction peak is always the strongest peak.The grain size of Mg₂Si thin films which were prepared by in-situ annealing at 550°C for 4 h is continuously compact,and the surface has a high degree of crystallinity.The intensity of Mg₂Si diffraction peaks increases first and then decreases with increasing of annealing temperature at 400-600?for 4 h,which is in accordance with the change of thin film sheet resistance.The square resistance of the film appears minimum value at the annealing temperature 550?.Then we studied the influences of the sputtering order of Si and Mg on the CSSM of Mg₂Si thin films.A Si film was deposited after depositing a sputtered Mg film on a glass substrate.The Mg film deposition times were 14 mins,16 mins,18mins,20 mins,and 22 mins,respectively,and the Mg film deposition rate was 80nm/min.The Si film deposition time was 25 minutes and the deposition rate was 10nm/min.The film samples which were prepared by in-situ annealing at 550°C for 4 h were characterized by X-ray diffractometry and scanning electron microscopy.The test results show thatMg₂Si films were successfully prepared when different thicknesses of Mg films were exchanged for the sputtering sequence.When the Mg films were sputtered for 16 mins,the Mg₂Si films exhibited the highest intensity of diffraction peaks and the most continuously.When the thickness of Mg films increase,the intensity of Mg₂Si diffraction peak increases first and then decreases.When the sputtering time exceeds 18 minutes,the diffraction peak of Mg appears.Finally,the preparation of multilayer Mg₂Si thin films were investigated.Two and three layers Si/Mg thin films were alternately sputtered on glass substrates.The influences of the in-situ annealed Mg₂Si thin films were studied under different annealing temperatures and Si/Mg sputtering thickness.The results show that when the Si and Mg thin films are thinner,the Mg₂Si thin film does not grow regardless of the two or three-layers sputtering.With the increase of the sputtering thickness,the intensity of Mg₂Si diffraction peaks increases greatly.The diffraction peak intensity of Mg₂Si thin film is the strongest and the best surface morphology at annealing temperature 550?.Too low or too high annealing temperature are not conducive to the growth of Mg₂Si thin films.