Thermoelastic stresses in multilayered beams

The functionality and reliability of multilayered systems are strongly influenced by thermoelastic stresses. Recently Hsueh formulated a closed-form solution [Hsueh, Thermal stresses in elastic multilayer systems, Thin Solid Films 418 (2002) 182] by decomposing the total strain into a uniform strain component and a bending strain component in order to overcome the complexity of the traditional analytical models. The present study develops an alternative analytical model in terms of the curvature radius of the neutral axis for zero normal strain and the normal strain at the interface between the substrate and the films. Numerical results are calculated for thermoelastic stresses in five-layer (AlGa)As laser diodes. Also two approximate models for the case of multilayered films on a thick substrate are obtained.