Synthesis and stress analysis of germanium nanocrystals embedded in dielectric matrices

Abstract

A study of the influence of annealing ambient and Ge concentration on the nanocrystal formation revealed an important role of H2 in assisting the germanium diffusion. Next, Ge nanocrystals were synthesized in an HfAlO matrix, which suggested that the growth of Ge nanocrystals in HfAlO were more difficult as compared to those in SiO2. The work was then focused on the quantitative analysis of stress states of Ge nanocrystals. By correlating the stress with the size, shape, density, distribution and quality of nanocrystals, it is possible to describe the kinetic factors influencing the nanocrystal formation and the stress evolution. Subsequently, several methods were proposed to alter the stress state of Ge nanocrystals, namely, annealing technique, capping stressor and dielectric matrix. Finally, the study showed that the pre-patterned substrate had a significant effect on the diffusion of Ge atoms and hence the formation and stress states of nanocrystals.