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We examined the formation of locally strained Ge nanostructures sandwiched between Ge1−x Sn x stressors using metal-organic chemical vapor deposition method. We have investigated the microscopic local strain and stress in the Ge/Ge1−x Sn x heterostructures using synchrotron microdiffraction and finite element method calculation. The microdiffraction measurement for an asymmetric lattice plane enables directly quantitative evaluation of the strain value of an individual Ge fine line structure with a few tens of nanometers width. An in-plane compressive strain value of 0.9% is achieved for a 30 nm-width Ge line with Ge1−x Sn x stressors, which corresponds to a compressive stress of 1.2 GPa.

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<div class="section abstract"><div class="htmlview paragraph">In electrified automobiles, wind noise significantly contributes to the overall noise inside the cabin. In particular, underbody airflow is a dominant noise source at low frequencies (less than 500 Hz). However, the wind noise transmission mechanism through a battery electric vehicle (BEV) underbody is complex because the BEV has a battery under the floor panel. Although various types of underbody structures exist for BEVs, in this study, the focus was on an underbody structure with two surfaces as inputs of wind noise sources: the outer surface exposed to the external underbody flow, such as undercover and suspension, and the floor panel, located above the undercover and battery. In this study, aero-vibro-acoustic simulations were performed to clarify the transmission mechanism of the BEV underbody wind noise. The external flow and acoustic fields were simulated using computational fluid dynamics. The vehicle structural vibration and sound fields of the interior and exterior cabin were analyzed using vibroacoustic models consisting of three subsystems modeled by the finite-element or boundary-element method: The first is an underbody structure finite-element model containing a white body, suspension, battery, and undercover; the second is the interior cabin space boundary-element model; the third is the exterior cabin space finite-element model for analyzing acoustic radiation resulting from vehicle structural vibration for the small space between the floor panel and battery, the motor room and the under-vehicle space between the ground and undercover. The analysis results using the vehicle model reveal that the pressure fluctuations acting on the floor panel are more-dominant inputs for cabin noise than those acting on the outer surface. The pressure fluctuation acting on the floor panel is affected by the acoustic mode of the space between the battery and the floor panel.</div></div>

We have investigated the selective growth of a Ge 1%x Sn x epitaxial layer on a line/space-patterned SiO 2 /Si substrate by metal-organic chemical vapor deposition. We examined the behavior of a Sn precursor of tributyl(vinyl)tin (TBVSn) during the growth on Si and SiO 2 substrates and investigated the effect of the Sn precursor on the selective growth. The selective growth of the Ge 1%x Sn x epitaxial layer was performed under various total pressures and growth temperatures of 300 and 350 °C. The selective growth of the Ge 1%x Sn x epitaxial layer on the patterned Si region is achieved at a low total pressure without Ge 1%x Sn x growth on the SiO 2 region. In addition, we found that the Sn content in the Ge 1%x Sn x epitaxial layer increases with width of the SiO 2 region for a fixed Si width even with low total pressure. To control the Sn content in the selective growth of the Ge 1%x Sn x epitaxial layer, it is important to suppress the decomposition and migration of Sn and Ge precursors.