Effect of deposition conditions on the thermal stability of Ge layers on SiO2 and their dewetting behavior

Resonant light scattering properties of dielectric particles are highly sensitive to particle shapes and optical parameters of particle/substrate systems. To obtain submicron-sized Ge particle arrays of interest for applications in the near-infrared spectral range, we studied the breakup of relatively thick (60 nm) Ge layers on SiO2 caused by dewetting. It was found that the mechanism of the dewetting process depends on the temperature and the method of initial Ge layer deposition. The Ge layers, deposited using a Knudsen cell, were transformed into Ge particles by solid-state dewetting. The particle shape was determined by the kinetics of surface processes. The particle formation from Ge layers, grown by the Ge evaporation using an electron beam, requires their melting. The Ge droplet solidification on SiO2 after the liquid-state dewetting creates the particles of identical shapes close to the hemisperical, indicating that they are formed in the near equlibrium conditions. The scattering magnitude of contact angles reflects the deviation degree of the particle formation conditions from the thermodynamically equilibrium.