Formation of atomic-scale germanium quantum dots by selective oxidation of SiGe/Si-on-insulator

Abstract

A complementary metal-oxide-semiconductor-compatible method is proposed to form atomic-scale germanium (Ge) quantum dots $\text{(<10\hspace{0.17em}}\mathrm{nm})$ for application in single-electron devices or optical devices. The formation of Ge quantum dots is realized by the Ge atoms’ segregation and agglomeration during thermal oxidation of ${\mathrm{Si}}_{\text{1−x}}{\mathrm{Ge}}_x$ alloys. The size and distribution of the Ge dots are determined by conditions of thermal oxidation process and Ge content in the alloys. An average Ge-dot size of 5.1 nm with standard deviation of 1.79 nm and a comparatively uniform spatial distribution (dot density of ${\text{7.9×10}}^{11}\hspace{0.17em}{\mathrm{cm}}^{\text{−2}})$ could be obtained by selective oxidation of ${\mathrm{Si}}_{\text{0.85}}{\mathrm{Ge}}_{\text{0.15}}/\mathrm{Si}$ -on-insulator structure.