Thickness influence on spinodal decomposition in In0.2Ga0.8As/GaAs low temperature growth

Abstract

A transmission electron microscopy study of composition modulation in In0.2Ga0.8As/GaAs(001) structures grown at 200°C by atomic layer molecular beam epitaxy is reported, have observed that, at low growth temperature, phase separation is highly dependent on the epilayer thickness. For In0.2Ga0.8As/GaAs(001), a critical layer thickness for the appearance of composition modulation in low temperature growth is found to be between 80nm and 300nm. Epitaxial growth of III-V compounds heterostructures is used for tailoring the opto- and microelectronic properties of a wide range of devices. In these systems, reticular misfit induced stresses drive morphological and compositional instabilities that affect their performance. Elastic strain due to the reticular misfit in a structure with inhibited plastic relaxation seems to be a fundamental factor for spinodal decomposition to take place. The temperature for bulk decomposition is much lower than for deposition driven modulation.