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The Ge depth profile and generation of dislocations associated with oxidation of SiGe-on-insulator (SGOI) substrates are examined from the viewpoint of the temperature dependence. It is found that Ge profiles in SGOI layers after oxidation are strongly dependent on the oxidation temperature. This fact is explained by the competitive process between the accumulation of Ge atoms at the SiGe/thermal oxide interface, determined by the oxidation rate, and Ge diffusion toward substrates during oxidation of SGOI substrates. While the abrupt Ge profile obtained by low-temperature oxidation causes the generation of dislocations, SGOI layers with high Ge content and no dislocations can be achieved by high-temperature oxidation. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Current-perpendicular-to-plane (CPP) geometrical giant magnetoresistance (GMR) single spin-valve (SPV) structures with synthetic antiferromagnets (SyAFs) as free layers were fabricated. The sample sizes range from micron to submicron. We demonstrate that SyAFs as free layers dramatically enhances the CPP-GMR ratio from 0.83% to 3.56% at room temperature and also double the resistance-area product in single SPV films. A study of the magnetic switching behavior by both experiment and single-domain thermal activation modeling shows that the CPP-GMR SPV with SyAF structure approaches that of a single-domain magnet even with low aspect ratio of 1 as long as its size diminishes to ∼0.18 μm2. The single-domain structure brings size-independent magnetic switching field when the aspect ratio is 1. The large GMR ratio at room temperature, single-domain structure and size-independent magnetic switching field demonstrate the great potential of CPP-GMR SPVs with SyAF free layers for use in future ultrahigh density magnetic storage devices. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We demonstrate the fabrication of dislocation-free strain-relaxed SiGe-on-insulator (SGOI) layers as virtual substrates for strained Si-on-insulator (SOI) metal–oxide–semiconductor field-effect transistors (MOSFETs) by forming SiGe-mesa structures and successive oxidation. A pseudomorphic Si[sub 0.9]Ge[sub 0.1] layer on a SOI layer was etched to form mesa structures. After the oxidation of the mesas, thin (<100 nm) Si[sub 0.85]Ge[sub 0.15] mesa structures were formed on the buried oxide layer. It was found that the mesas with a diameter smaller than 3 μm were almost completely relaxed after oxidation at 1200 °C, without generating any threading dislocations and crosshatch patterns, which generally exist in the relaxed SiGe layers on bulk Si substrates. The formation of SGOI mesas before oxidation has the potential to provide ideal SGOI virtual substrates for strained SOI MOSFETs. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A promising fabrication method for a Si[sub 1-x]Ge[sub x]-on-insulator (SGOI) virtual substrate and evaluation of strain in the Si layer on this SGOI substrate are presented. A 9-nm-thick SGOI layer with x=0.56 was formed by dry oxidation after epitaxial growth of Si[sub 0.92]Ge[sub 0.08] on a silicon-on-insulator substrate. During the oxidation, Ge atoms were rejected from the surface oxide layer and condensed in the remaining SGOI layer, which was partially relaxed without introducing a significant amount of dislocations. It is found from the analysis of the Raman spectra that the strained Si layer grown on the SGOI layer involves a tensile strain of 1%. This strained Si on the SGOI structure is applicable to sub-100-nm metal–oxide–semiconductor field-effect transistors. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Observes high-efficiency laser oscillation by means of resonant optical pumping in a planar microcavity laser. Measurement of the excitation power density and the differential energy conversion efficiency; Attribution of high efficiency to the absorption enhancement effect in the microcavity; Exhibition of output power saturation.