Au induced low-temperature formation of preferentially (111)-oriented crystalline Ge on insulator

Abstract

The effects of Au insertion in solid-phase crystallization for amorphous Ge films on SiO2/Si substrates were investigated to achieve oriented crystalline Ge. After high-temperature annealing above 300 °C, Au atoms were highly diffused in the amorphous Ge layer. The resulting crystalline Ge consisted of random grains formed by crystal nucleation in the entire Ge region. However, when annealing temperature was decreased to below 250 °C, Au atoms were localized at their initial position even after a long annealing (20 h). Moreover, formation of preferentially (111)-oriented crystalline Ge was achieved without using the metal-induced layer-exchange crystallization method. These results suggest that crystal nucleation preferentially occurs at the amorphous Ge/Au interface, and subsequently the nucleus growth progresses into the Ge layer.