Si 모재 위의 $Si_xGe_{1-x}$ 박막에서 부정합 전위와 임계두께에 관한 연구

Study on Misfit Dislocations and Critical Thickness in a $Si_xGe_{1-x}$ Epitaxial Film on a Si Substrate

The critical thickness of an epitaxial film on a substrate in electronic or optoelectronic devices is studied on the basis of equilibrium dislocation analysis. Two geometric models, a single dislocation and an array of dislocations in heteroepitaxial system, are considered respectively to calculate the misfit dislocation formation energy. The isotropic linearly elastic stress fields for the models are obtained by means of complex potential method combined with alternating technique, and are used for calculating the formation energies. As a result, the effect of elastic mismatch between film and substrate on critical thickness is presented and $Si_xGe_{1-x}/Si$ epitaxial structure is analyzed to predict the critical thickness with varying germanium concentration.