Fabrication of a polycrystalline SiGe- and Ge-on-insulator by Ge condensation of amorphous SiGe on a SiO2/Si substrate

Abstract

Abstract 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 ∼211 cm2 · V−1 · s−1 is achieved with a hole concentration of ∼3.7 × 1015 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 ∼5.1 × 1018 cm−3 and mobility of ∼15 cm2 · V−1 · 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.