Fabrication Aspects of Germanium on Insulator from Sputtered Ge on Si-Substrates

Abstract

Germanium (Ge) metal-oxide-semiconductor-field-effect transistors (MOSFETs) have higher carrier mobilities than Si. We have studied the growth of high quality single-crystal germanium on insulator (GOI) using rapid liquid-phase epitaxial growth and defect-necking techniques. Stable single-crystal Ge growth was seen at a temperature of 925 °C, below the melting point of Ge. At and above the Ge melting temperature, we found Ge segregating into balls. Defect-free crystals were grown from the semisolid state of Ge. The defect-necking technique was improved with an underlying insulator undercut to minimize dislocation or stacking faults. Up to 60 μm long crystal-on-insulators were grown. Strain analysis of grown Ge was studied using Raman spectroscopy, and grown films were found to have tensile strain.