A comparative study of defect formation in GaAs nanocrystals selectively grown on nanopatterned and flat Si(001) substrates.

Crystal defects present in GaAs nanocrystals ∼15-50 nm in diameter and grown by metal organic vapor phase epitaxy on top of two different nanopatterned Si(001) substrates (nanopillars and nanotips with ∼40-80 nm openings embedded in a SiO matrix) and on a planar substrate, have been investigated by means of atomic-resolution aberration-corrected scanning transmission electron microscopy. Conditions of their formation are discussed. The defect analysis of the three GaAs/Si systems reveals a higher defect density in the GaAs crystals grown on nanopillars as compared to those grown on nanotips and the planar substrate, possibly concomitant to the atomic-scale irregularities identified at the patterned Si(001) nanopillars.

Selective Nucleation of GaAs on Si Nanofacets.

The early growth stage of GaAs by metal organic vapor phase epitaxy on a novel kind of Si substrate is investigated. The substrate consists of nanotips (NTs) fabricated on a Si(001) wafer by means of lithography and reactive ion etching. 3D GaAs nanocrystals are found to nucleate with a probability of 90% on the (n0m), (-n0m), (0nm), and (0-nm) facets (n, m integers) of these NTs.

Bi-modal nanoheteroepitaxy of GaAs on Si by metal organic vapor phase epitaxy.

Nano-heteroepitaxial growth of GaAs on Si(001) by metal organic vapor phase epitaxy was investigated to study emerging materials phenomena on the nano-scale of III-V/Si interaction. Arrays of Si nano-tips (NTs) embedded in a SiO matrix were used as substrates. The NTs had top Si openings of 50-90 nm serving as seeds for the selective growth of GaAs nano-crystals (NCs).

Structural and optical characterization of GaAs nano-crystals selectively grown on Si nano-tips by MOVPE.

We present the nanoheteroepitaxial growth of gallium arsenide (GaAs) on nano-patterned silicon (Si) (001) substrates fabricated using a CMOS technology compatible process. The selective growth of GaAs nano-crystals (NCs) was achieved at 570 °C by MOVPE. A detailed structure and defect characterization study of the grown nano-heterostructures was performed using scanning transmission electron microscopy, x-ray diffraction, micro-Raman, and micro-photoluminescence (μ-PL) spectroscopy.

Structural defects in cubic semiconductors characterized by aberration-corrected scanning transmission electron microscopy.

The development of new electro-optical devices and the realization of novel types of transistors require a profound understanding of the structural characteristics of new semiconductor heterostructures. This article provides a concise review about structural defects which occur in semiconductor heterostructures on the basis of micro-patterned Si substrates. In particular, one- and two-dimensional crystal defects are being discussed which are due to the plastic relaxation of epitaxial strain caused by the misfit of crystal lattices.

Crystal structure of the ternary silicide Gd2Re3Si5.

A single crystal of the title compound, the ternary silicide digadolinium trirhenium penta-silicide, Gd2Re3Si5, was isolated from an alloy of nominal composition Gd20Re30Si50 synthesized by arc melting and investigated by X-ray single-crystal diffraction. Its crystal structure belongs to the U2Mn3Si5 structure type. All atoms in the asymmetric lie on special positions.