Bandgap Tunable Thin Films Based On Gallium Oxide By Magnetron Sputtering

Both Ga₂O₃ and In₂O₃ are transparent oxide semiconductor materials with direct bandgap.Monoclinic?-Ga₂O₃ is transparent in the deep ultraviolet band,but its application in many fields is limited because of its wide band gap?4.9 e V?.In₂O₃ has excellent photoelectric performance and its optical band gap is generally less than 3.7 e V,which is widely used in many photoelectric fields.The band gap width of gallium and indium oxide materials can be adjusted between 3.7?4.9 e V,which makes up for the deficiency of both.Therefore,it is very necessary to study the material of(Ga_xIn_1-x)₂O₃ thin film.In this paper,(Ga_xIn_1-x)₂O₃ thin film material is prepared by magnetron sputtering process,which is mainly divided into two parts.In the first part,the effects of annealing temperature on the structure properties,optical properties and bandgap width of thin films were studied.For the preparation of mismissible m-(Ga_xIn_1-x)₂O₃ material,Ga content increases with the increase of annealing temperature.At 600??900?,the particles were uniformly distributed and RMS was relatively small.At 1000?,the RMS increases with larger grains.Indium atoms have been incorporated into the?-Ga₂O₃ lattice and gallium atoms have been incorporated into the c-In₂O₃ lattice.The transmittance is above 90%,with single absorption edge and uniform film thickness.At 600??800?,the annealing temperature is independent of the band gap width.When the temperature is?900?,the band gap increases with the increase of the temperature and reaches the maximum at 1000?.For the preparation of monoclinal material?-(Ga_xIn_1-x)₂O₃,Ga content increases and then decreases with the increase of annealing temperature,and reaches the peak at 1000?.At600?,the surface is dense and uniform particles resembling the tip of a needle;at 700??900?,the surface is uniformly distributed fine particles;at 1000??1100?,there are larger grains.RMS increases with increasing temperature.Indium atoms in monoclinic films have been incorporated into the matrix?-Ga₂O₃ lattice,and the higher the temperature,the higher the crystal quality of the sample.At 1100?,the transmittance is low,the interference fringe is weak and the surface is rough.At 600??800?,the band gap width remains the same;the band gap is the largest at 900?.The second part:the influence of element content in(Ga_xIn_1-x)₂O₃ film on the structure property,optical property and band gap width of the film was studied.For 1000? annealed(Ga_xIn_1-x)₂O₃ film,the Ga content x increases linearly with the thickness ratio Ga/?In+Ga?increasing.For films with Ga content of x between 0.11 and 0.55,both cubic and monoclinic structures exist.When Ga content x is greater than 0.74,only monoclinic structure appears in the film.It indicates that Ga ion has been integrated into the lattice of In₂O₃.The In ion is incorporated into the Ga³⁺bit of the Ga₂O₃ lattice.The surface was composed of dense and uniform particles with RMS less than 5nm.Film surface smooth and uniform thickness.The transmittance is greater than 86%.With the increase of Ga content,the absorption edge moves to the direction of shorter wavelength.The bandgap value increases with the increase of Ga content,and the bandgap bending parameter is b=1.225±0.221 e V.For the 900? annealed(Ga_xIn_1-x)₂O₃ film,the film has a uniform distribution of fine granular morphology,where the sample surface of x=0.6 has only scattered small circular particles.RMS are relatively small and smooth.When Ga content x of 0.12?0.61,only the diffraction peak of cubic phase exists,while when gallium content x of 0.83?0.91,only the monoclinic diffraction peak exists.The transmittance of films is greater than 88%.With the increase of Ga content x,the absorption edge moves to the direction of shorter wavelength.The bandgap value increases with the increase of Ga content,and the bandgap bending parameter is b=2.7±0.189 eV.