Nanostructured hybrid material based on highly mismatched III–V nanocrystals fully embedded in silicon

Abstract

InAs quantum dots were directly grown on (100) planar silicon surfaces and embedded in a defect‐free silicon matrix after a multi‐step silicon overgrowth and annealing process performed by molecular beam epitaxy. Detailed high‐resolution transmission electron microscope investigations allow to follow within several steps the formation process of nearly fully relaxed InAs nanocrystals embedded in a defect‐free and planar silicon layer. The lattice mismatch between InAs and Si is almost fully accommodated by closed misfit dislocation loops at the III–V silicon interface, which suppresses the generation of threading dislocations in the embedding silicon matrix. InAs QDs embedded in defect‐free silicon.

Single photon emission up to liquid nitrogen temperature from charged excitons confined in GaAs-based epitaxial nanostructures

“…The emitter, driven non-resonantly by the CW laser source, preserves its quantum nature of the emission process up to at least T ¼ 80 K. The g (2) (0) value significantly below the 0.5 limit indicates that the charge exciton state confined in the CQD can be considered as a true single photon generator able to operate above the liquid nitrogen temperature. This observation is a promising result in the context of further research on triggered single photon sources made within the GaAstechnology, especially when regarding the integration with silicon, 37 silicon-on-insulator, 38 or germanium-on-insulator 39 substrates in order to create hybrid platforms for the development of future high-performance CMOS-based photonic systems 40 or photonic MEMS. 41 Utilization of considered in this letter CQD nanostructures with compact cooling system could allow to create a robust, handy, and fully operational single photon source device for quantum cryptography protocols like, for example, free-space quantum key distribution.…”

The epitaxial growth and unique morphology of InAs quantum dots embedded in a Ge matrix

“…AFM images (1 × 1 µm 2 and 5 × 5 µm 2 ) of the samples are shown in figures 6(b) and (c) (sample J), and figures 6(d) and (e) (sample K). A smooth epi-surface with atomic steps could be clearly seen for both samples, indicating the QDs have been fully covered by a Ge layer, which is different from Si/InAs/Si where numerous nanoholes as large as QDs were depicted after Si overgrowth [7]. However, surface threading dislocations (TDs) with a density of 3-5 × 10 8 cm −2 were estimated for both 40 nm and 200 nm Ge samples by counting the dark holes in the AFM images.…”

“…Later, high uniformity InAs QDs grown on Si substrates were demonstrated with a dot density of ∼10 11 cm −2 and 1.3 µm wavelength photoluminescence emission [5,6]. Recently, nearly strain-relaxed InAs QDs embedded in a defect-free Si matrix have been demonstrated by a combination of several steps of overgrowth and postgrowth annealing processes [7]. As for the epitaxial growth of InAs QDs directly on Ge, InAs and InGaAs islands were grown on a 6 • offcut Ge (100) substrate by metalorganic vapour phase epitaxy.…”

A Novel One-Pot Synthesis of PVP-Coated Iron Oxide Nanoparticles as Biocompatible Contrast Agents for Enhanced T2-Weighted MRI

“…In this context, superparamagnetic iron oxide nanoparticles (SPIONs) have attracted significant attention from researchers for their exceptional characteristics, such as high relaxivity, superior magnetic properties, non-toxicity, and the ability to target specific cells or tissues. Compared to Gd-based contrast agents, SPIONs have proved to be promising nanomaterials for a wide range of biomedical applications [3][4][5][6].…”