| With the development of semiconductor industry,the electronic devices with high integration and high performance require that the components should have smaller size and higher performance.When the size of the material reaches the nanometer scale,the performance of the materials,as well as indium-based semiconductor materials,is more significantly affected by their structure.Dynamical observation of structural evolution of indium-based materials is the basis of understanding structural evolution mechanism and developing structural modification method.It is of great significance for optimization of the material performance and designing novel indium-based high-performance devices.In this thesis,the high energy electron beam in transmission electron microscope is used to excite the structural evolution of indium-based semiconductor materials,and then investigate the structural evolution mechanism.The main research contents and results are as follows:1.Indium phosphide particles are decomposed under the irradiation of conversive electron beam,and indium nanoparticles with different sizes are formed around the In P particles.The number and size of indium nanoparticles increase with the increase of the irradiation times.The closer to the In P precursor,the larger and more dispersed.The main factors affecting the decomposition of indium phosphide and electron beam fragmentation include electron beam dose rate,irradiation time,sample size and carbon film thickness.The local temperature rise associated with electron beam irradiation plays a leading role in the fragmentation process.2.Indium nanoparticles are oxidized by electron beam irradiation and evolve into different structures under electron beam irradiation with different energy.(1)Under 200 ke V electron beam irradiation,the nanoparticles transform into yolk-shell structure.The nanoparticles of different sizes have the same oxide limiting thickness of～ 4.75 nm.(2)Under 300 ke V electron beam irradiation,the nanoparticles evolved to hollow structure,and the oxide layer thickness increases with the increase of particle diameter;the structure evolution is closely related to particle size and electron beam dose rate,and small nanoparticles will eventually evolve into "petal" shape structure under high dose rate electron beam irradiation.(3)Electron beam heating promote the migration of In species through the oxide layer,resulting in the formation of yolk-shell/hollow structure.The difference in morphology evolution results from elastic scattering.The elastic scattering is more serious under 300 ke V electron beam irradiation,which leading to the formation of gaps in the oxide layer,which provide fast outward diffusion paths for indium ion.However,the oxide layer generated is more dense under 200 ke V electron beam irradiation,and the indium core is more easily confined in the particle center.3.Indium Selenide nanosheets were damaged by electron beam irradiation,and indium oxide grains were formed locally.Compared with the surface,it is easier to form indium oxide grains at the edge of the indium selenide nanosheet at the edge of the indium selenide nanosheet at a lower dose.The growth of indium oxide is mainly along the(222)plane in a layer-by-layer manner.Indium oxide nucleates preferentially at the step,followed by surface reconstruction,to reduce the surface energy. |
