Ultrathin epitaxial germanium on crystalline oxide metal-oxide- semiconductor-field-effect transistors

Ultrathin films of single crystal Ge (100 Å or less) have been grown epitaxially on a lattice matched high- κ crystalline oxide, lanthanum-yttrium-oxide, in turn grown on Si. Back-gated germanium-on-insulator field-effect transistors have been fabricated and measured from these germanium-on-insulator layers for Ge layers in the 30-600 Å range. The best devices exhibit an Ion Ioff ratio over 103 at room temperature and 105 at T=77 K. These ultrathin devices can be fully depleted and inverted, enabling both p and n channel operation in the same device. © 2005 American Institute of Physics.