Formation, evolution, and prevention of thermally induced defects on germanium and silicon upon high-temperature vacuum annealing

This Letter reports the formation, evolution, and prevention of thermally induced defects on germanium upon high-temperature (up to 890 $°$C) vacuum (⁠$2×10−6$ Torr or $2.67×10−6$ mbar) annealing. It is found that the shape of defects evolves depending on the annealing temperature and duration. The defect shape can be classified into three groups (pyramid, expanded pyramid, and doughnut), considering the interplay of chemical desorption and surface diffusion. The effects of annealing conditions on the density and size of defects are also investigated with scanning electron microscopy and atomic force microscopy. To prevent thermally induced defects, a simple covering method is proposed and demonstrated. In addition, formation and prevention of defects resulting from high-temperature (1150 $°$C) vacuum annealing are applied to silicon.