Fabrication of Ge-on-Si substrates for the integration of high-quality GaAs nanostructures on Si

Ge-on-Si substrates, made by a thin Ge relaxed layer with a low threading dislocation density and reduced surface roughness deposited on Si, are capable of accommodating the mismatch between GaAs and Si substrate and can be used for the growth of high quality AlGaAs/GaAs layers and of GaAs nanostructures by droplet epitaxy, while maintaining a low thermal budget compatible with the integration of CMOS devices.