The Calculation Of Strain Field In Semiconductor Heteroepitaxy Material And Quantum Dot Relax Degree

This work was supported by the National "973" Basic Research Program of China "Theoretical and technical innovation on the compatibility issues of heterogeneous material for the monolithic integrated optoelectronic devices",and the National Natural Science Foundation of China "Investigation on long wavelength GaAs quantum heterogeneous structure materials based on strain mechanism".The materials of semiconductor hetero-epitaxy and quantum dots are widely used in the fields such as nano-electronics and optoelectronics. This dissertation adopted finite element methods to analyze the strain, stress and relax degree of the materials.Firstly,we analyzed the strain and stress distributions using finite element methods according to the papers referenced.Then the strain in the epilayer and substrate of InGaAs/GaAs system was also studied,and the influences of different heights of substrate and different contents of In were also discussed.Secondly,the distribution of strain energy and the strain relaxed degree,as functions of the aspect ratio in different shaped quantum dots, were studied using finite element method.The impact on strain relaxation: originating from the shape and the inter-island distance,was also quantitatively analyzed.The results indicate that when ignoring the surface energy,the relaxed degree ascends with the increase of the aspect ratio regardless of the shapes,among which the truncated pyramid quantum dots tend to be steady earlier than others.With the rise of the inter-island distance,the strain energy in the dots decreases,especially in the cubic dots.It is good reference for the relaxed degree on controlling the shapes of quantum dots.Finally,the study was summarized and viewed.