Growth And Properties Of Indium/Tin Doped Gallium Oxide Films

Ga₂O₃ has been widely used in metal oxide semiconductor field effect transistor,schottky barrier diode and ultraviolet photodetector due to its excellent performance.Ga₂O₃ has a large bandgap,so regulating its bandgap has always been the focus of research.In this paper,Ga₂O₃ film is used as the matrix,and In and Sn are used as the dopant.The effects of In and Sn doping on the structure,morphology,bandgap,photoluminescence and photoelectric properties of Ga₂O₃ films are studied.（1）By means of placing metal In wires on the Ga₂O₃ target,the amorphous（In Ga）₂O₃ films with tunable composition via only changing the length of In wires are successfully synthesized by magnetron sputtering.With the increase of In wire length,the In component content of the prepared amorphous（In Ga）₂O₃ film increases,and the bandgap can be adjusted from 4.81 e V to 4.63 e V.The purple and green luminescence peaks appear in the amorphous（In Ga）₂O₃ films with different In components.Ga₂O₃and amorphous（In Ga）₂O₃ film photodetectors are fabricated,and the performance of the film photodetectors are tested at the ultraviolet LED light source at 222 nm.The decay time of the（In Ga）₂O₃ film photodetector is significantly increased compared with that of the Ga₂O₃ film photodetector,and the（In Ga）₂O₃ film photodetector has a lower dark current.（2）The amorphous（In Ga）₂O₃ films are annealed in air atmosphere.The results show that annealing can improve the crystal quality of the films,and the phase separation occurs when the annealing temperature reaches 800℃.A large number of cavities are formed on the surface of（In Ga）₂O₃ films after annealing.The optical bandgap values of the（In Ga）₂O₃ films annealed at different temperatures are 4.68 e V,4.73 e V,4.84 e V and 4.89 e V,respectively.The red luminescence peak is from the radiative recombination of the V_Ga acceptor and VB.（3）The amorphous（Sn Ga）₂O₃ films with different Sn compositions are prepared and are annealed in air.Sn is successfully doped into the films and the annealed（Sn Ga）₂O₃ films exhibited a single phase.The optical bandgap values of the film can be adjusted within the range of 4.32 e V～4.68e V by changing the doping amount of Sn and performing annealing treatment.