Control of InGaAs facets using metal modulation epitaxy (MME)

Control of faceting during epitaxy is critical for nanoscale devices. This work identifies the origins of gaps and different facets during regrowth of InGaAs adjacent to patterned features. Molecular beam epitaxy (MBE) near SiO2 or SiNx led to gaps, roughness, or polycrystalline growth, but metal modulated epitaxy (MME) produced smooth and gap-free "rising tide" (001) growth filling up to the mask. The resulting self-aligned FETs were dominated by FET channel resistance rather than source-drain access resistance. Higher As fluxes led first to conformal growth, then pronounced {111} facets sloping up away from the mask.Comment: 18 pages, 7 figure

Molecular beam epitaxy of highly crystalline GeSnC using CBr4 at low temperatures

Tensile-strained pseudomorphic Ge1–x–ySnxCy was grown on GaAs substrates by molecular beam epitaxy using carbon tetrabromide (CBr4) at low temperatures (171–258 °C). High resolution x-ray diffraction reveals good crystallinity in all samples. Atomic force microscopy showed atomically smooth surfaces with a maximum roughness of 1.9 nm. The presence of the 530.5 cm−1 local vibrational mode of carbon in the Raman spectrum verifies substitutional C incorporation in Ge1–x–ySnxCy samples. X-ray photoelectron spectroscopy confirms carbon bonding with Sn and Ge without evidence of sp2 or sp3 carbon formation. The commonly observed Raman features corresponding to alternative carbon phases were not detected. Furthermore, no Sn droplets were visible in scanning electron microscopy, illustrating the synergy in C and Sn incorporation and the potential of Ge1–x–ySnxCy active regions for silicon-based lasers.The authors acknowledge support from the National Science Foundation under Grant Nos. DMR-1508646, CBET-1438608, and PREM DMR-2122041, the Center for Dynamics and Control of Materials is supported by the National Science Foundation under Award No. DMR-1720595, and additional support by the University of Texas at Austin.Center for Dynamics and Control of Material

Gas Source Techniques for Molecular Beam Epitaxy of Highly Mismatched Ge Alloys

Ge and its alloys are attractive candidates for a laser compatible with silicon integrated circuits. Dilute germanium carbide (Ge1−xCx) offers a particularly interesting prospect. By using a precursor gas with a Ge4C core, C can be preferentially incorporated in substitutional sites, suppressing interstitial and C cluster defects. We present a method of reproducible and upscalable gas synthesis of tetrakis(germyl)methane, or (H3Ge)4C, followed by the design of a hybrid gas/solid-source molecular beam epitaxy system and subsequent growth of defect-free Ge1−xCx by molecular beam epitaxy (MBE). Secondary ion mass spectroscopy, transmission electron microscopy and contactless electroreflectance confirm the presence of carbon with very high crystal quality resulting in a decrease in the direct bandgap energy. This technique has broad applicability to growth of highly mismatched alloys by MBE

GROWTH OF 1.5 µm GaInNAsSb VERTICAL CAVITY SURFACE EMITTING LASERS BY MOLECULAR BEAM EPITAXY

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using self-linearized

optical remoting of ultrafast charge packet