In sophisticated semiconductor devices, transistors may be formed on the basis of a high-k metal gate electrode structure provided in an early manufacturing phase, wherein an efficient strain-inducing mechanism may be implemented by using an embedded strain-inducing semiconductor alloy. In order to reduce the number of lattice defects and provide enhanced etch resistivity in a critical zone, i.e., in a zone in which a threshold voltage adjusting semiconductor alloy and the strain-inducing semiconductor material are positioned in close proximity, an efficient buffer material or seed material, such as a silicon material, is incorporated, which may be accomplished during the selective epitaxial growth process.