Fabrication of a Polycrystalline SiGe- and Ge-on-insulator by Ge Condensation of Amorphous SiGe on a SiO2/Si Substrate

In this work, the Ge condensation effect of amorphous SiGe on a SiO2/Si substrate is systematically investigated. As Ge condensation proceeds, the Ge content gradually enriches from an initial 0.24-1.0 with improving crystal quality. The enlargement of the grain size results in gradual roughening of the surface roughness. As the Ge content reaches 0.36, a high hole mobility of similar to 211 cm(2)center dot V-1 center dot s(-1)is achieved with a hole concentration of similar to 3.7 x 10(15)cm(-3). As the Ge content further accumulates, the grain number increases resulting in a higher hole concentration. The film mobility gradually deteriorates probably due to the following factors: strong impurity scattering at high hole concentration, increase of grain boundaries, decrease of SiGe thickness, and increase of surface roughness. A polycrystalline Ge-on-insulator with a hole concentration of similar to 5.1 x 10(18)cm(-3)and mobility of similar to 15 cm(2)center dot V-1 center dot s(-1)is ultimately fabricated. The investigation provides a promising method to fabricate a high hole mobility SiGe-on-insulator platform from low-cost amorphous SiGe.