Low-temperature epitaxial growth of Ge on Si, towards a cost-effective substrate for III-V solar cells

Epitaxial Ge on Si could be used as a virtual Ge substrate for III-V solar cells which has superior mechanical properties and is less expensive than Ge wafers. Aluminium assisted crystallization via magnetron sputtering offers a low-cost method allows the epitaxy of Ge on Si at low temperatures. The novelty of our one-step aluminium-assisted crystallization of Ge epitaxy on Si lies in the elimination of the post-deposition annealing step. Our process simply requires sequential depositions of Al and Ge films via magnetron sputtering in the same chamber without breaking the vacuum. By applying an insitu low-temperature (100 °C) heat treatment in between Al and Ge depositions, Ge epitaxy on Si is achieved.