Calculation of critical layer thickness considering thermal strain in Si1-xGex/Si strained-layer heterostructures

In this article, interactions of thermal strain in growth of Si1-xGex strained-layers on Si are analyzed. A formula of critical layer thickness (h(c),) is obtained based on energy balance considering thermal strain under the assumption that the screw dislocation energy density equals to the sum of the areal strain energy density and thermal strain energy density. The relationship between the thermal expansion coefficient associated with thermal strain and Ge content x is linear. Our calculated values for h(c) of Si1-xGex strained layers on Si substrates versus mismatch, considering thermal strain, are better agreement with measurements of h(c) by People and Bean. (C) 1998 American Institute of Physics.