The Study Of In₂O₃-based Diluted Magnetic Semiconductor Prepared By Sol-Gel Method

Diluted magnetic semiconductors(DMSs),i.e.,semiconductors doped with magnetic metallic elements,have been the frontier research objects in the field of condensed state physics and material science because of the possibility of assembling charge and spin degrees of freedom in single substance.The mostly researched systems are magnetic transition element doped ZnO,TiO₂,SnO₂ and In₂O₃.To integrate electronics,magnetics and photonics for next generation multifunctionai devices,it will be important to search for a magnetic semiconductor with tunable carrier density,high mobility and magnetic moment as well as optical transparency.In this thesis,transition metallic Fe and Fe/Sn co-doped were introduced into In₂O₃ lattices by Sol-gel method to compound films and powders.On the base of large amounts of processing explorations,we made a primary discussion and analysis for the observed room-temperature(RT) ferromagnetic state in the samples as well as its origin in combination with the structure,the morphology,the optical characteristic and the magnetic behavior of the samples.Firstly,in this dissertation,the films and powders of(In_1-xFe_x)₂O₃ and (In_0.9-xFe_xSn_0.1)₂O₃ which used In(NO₃)₃·4.5H₂O,Fe(NO₃)₃·9H₂O,SnCl₄.5H₂O, acetylacetone and ethylene glycol monomethl ether as law materials were prepared by Sol-gel method in the air.Samples were heat-treated at 110℃,annealed at 500℃. The preparation craft was carried out on samples.It turned out that the best sintering craft was sintering at 500℃from the perspective of crystal.Secondly,the films samples of the(In_1-xFe_x)₂O₃ and(In_0.9-xFe_xSn_0.1)₂O₃,for the x=0,the curve is diamagnetic;the saturation magnetization increased as the increasing of Fe content when Fe content below 20at.%,it might be the reason of the enhancing of the exchange in the magnetic ions,the largest magnetic moment reached at x=0.2;above 20at.%,the saturation magnetization decreased,this maybe due to a formation of impurity phase leading to a destruction of the cubic bixbyite crystal structure of the host lattice.The power samples of(In_1-xFe_x)₂O₃,for the x=0, the curve is diamagnetic;for the x=0.05,the curve is paramagnetism,the saturation magnetization increased as the increasing of Fe content,the largest magnetic moment reached at x=0.2,it's the same as the films of(In_1-xFe_x)₂O₃.When the x= 0.3,the curve show a trend of the composition of paramagnetism and ferromagnetism.The same kind samples with different forms of x=0.05 and 0.3 have completely different magnetic property,the reason may be due to the defect. The power samples of(In_0.9-xFe_xSn_0.1)₂O₃,the curves gradually change from antimagnetism to paramagnetism to the composition of paramagnetism and ferromagnetism.It maybe due to the major role of the non-magnetic Sn ions.But such kind of the films samples have significant magnetism,maybe due to defects.Finally,we compared the magnetic behavior of the two series of(In_1-xFe_x)₂O₃ and(In_0.9-xFe_xSn_0.1)₂O₃ samples.It find out that in the Fe doped In₂O₃-based,the orderly ferromagnetism is destroyed by the introduction of additional non-magnetic Sn ions.The magnetization of the samples are reduced or disappear.In a word,the cation defects and oxygen vacation lead to change of carrier concentration in this system,ultimately contribute to the magnetism in coupled exchange.