Calculation of Stress Concentration at the Edge of Island Layer: Demonstration for GaAs/Si

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Abstract
An improved shear lag analysis was proposed to precisely calculate longitudinal stress distribution in hetero- structures with island layers. It is assumed that each layer consists of many imaginary thin layers in order to calculate internal stress distributions over the entire heterostructure. This method is applied to the calculation of stress in a GaAs/Si heterostructure whose GaAs layer is separated or selectively grown similarly to the island layer, in order to determine the effect of island layer on the concentration of stress at the island edge and on the reduction of stress in the GaAs layer. In the stress distribution in the Si layer close to the heterointerface, a sharp and high peak of tensile stress appears at the edge of the GaAs island layer with misfit dislocations. This stress distribution agrees with the experimental one measured by Raman scattering. The tensile stress in the GaAs layer with misfit dislocations can be clearly reduced by decreasing the length of the GaAs island layer.