Ultrathin-body Ge-on-insulator wafers fabricated with strongly bonded thin Al2O3/SiO2 hybrid buried oxide layers

An ultrathin-body Ge-on-insulator (GeOI) wafer having a bonded thin Al2O3/SiO2 hybrid buried oxide layer was fabricated using an epitaxially grown Ge film on Si as a Ge donor layer. The epitaxial Ge film was confirmed to have a negligibly low density of crystal-defect-induced p-type carriers and was successfully transferred to form the GeOI wafer. Strong Al2O3/SiO2 bonding effectively suppressed Ge exfoliation during the wafering process. The obtained device-grade GeOI layer and strong bonding strength between Al2O3 and SiO2 are potentially advantageous for future Si-based complementary metal–insulator–semiconductor (CMIS) fabrication processes utilizing large-diameter Si wafers.