[16p-D61-1~12] 15.5 Group IV crystals and alloys

▼ [16p-D61-11] Realization of vertical Ge/Si nanopillars by maskless etching of Ge quantum dot
nanostructures

〇Sergii Tutashkonko¹, Noritaka Usami¹ (1.Nagoya Univ.)

Keywords:Germanium, Silicon, Quantum dots

In this communication we report on the method to realize vertical Ge/Si nanopillars. The method consists of growing one layer of Ge quantum dot (QD) on Si substrate by gas-source molecular beam epitaxy and consecutive anisotropic etching of material around QDs with KOH. By growing the structures on (110)-oriented Si substrates, the etching profile is made vertical, since the stopping <111> planes for KOH etch are normal to the surface. The resulting structures are mushroom-shaped with Si “stems” and Ge “caps”. The size of stems and caps can be controlled by adjusting Ge growth conditions and KOH etch duration.
Such structures reduce the surface reflectivity and broaden optical absorption spectrum. In addition, the shape of these nanostructures coupled with low emissivity and high reflectivity of Ge as compared to Si, may be used to realize heat diodes for thermal insulation of the surface. In our communication we will present results of the shape and density control and analysis of physical properties of these nanostructures
Acknowledgement: This work was supported by Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST).