Devices Being Solar Cells (epo) Patents (Class 257/E25.007)
  • Patent number: 7141834
    Abstract: Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600° C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.
    Type: Grant
    Filed: June 24, 2005
    Date of Patent: November 28, 2006
    Assignee: California Institute of Technology
    Inventors: Harry A. Atwater, Jr., James M. Zahler