AbstractThe aim of the study is to discuss the most general aspects of semiconductor devices durability and reliability. The life time of a semiconductor device is related to the defect structure evolution of the crystalline and noncrystalline components involved. The driving force for the evolution of defect device structure is associated with relaxation processes of internal mechanical stresses. In this report the degradational effects in LEDs based on GaAs(Si) have been analyzed. The discussion of the necessity for research on composite materials creation is also included.