Self-assembling of Ge quantum dots in an alumina matrix

Abstract

In this work we report on a self-assembled growth of a Ge quantum dot lattice in a single 600-nm-thick $\text{Ge}+{\text{Al}}_{2}{\text{O}}_{3}$ layer during magnetron sputtering deposition of a $\text{Ge}+{\text{Al}}_{2}{\text{O}}_{3}$ mixture at an elevated substrate temperature. The self-assembly results in the formation of a well-ordered three-dimensional body-centered tetragonal quantum dot lattice within the whole deposited volume. The quantum dots formed are very small in size (less than 4.0 nm), have a narrow size distribution and a large packing density. The parameters of the quantum dot lattice can be tuned by changing the deposition parameters. The self-ordering of the quantum dots is explained by diffusion-mediated nucleation and surface-morphology effects and simulated by a kinetic Monte Carlo model.