Epitaxial III-V/Si Vertical Heterostructures with Hybrid 2D-Semimetal/Semiconductor Ambipolar and Photoactive Properties.

Hybrid materials taking advantage of the different physical properties of materials are highly attractive for numerous applications in today's science and technology. Here, it is demonstrated that epitaxial bi-domain III-V/Si are hybrid structures, composed of bulk photo-active semiconductors with 2D topological semi-metallic vertical inclusions, endowed with ambipolar properties. By combining structural, transport, and photoelectrochemical characterizations with first-principle calculations, it is shown that the bi-domain III-V/Si materials are able within the same layer to absorb light efficiently, separate laterally the photo-generated carriers, transfer them to semimetal singularities, and ease extraction of both electrons and holes vertically, leading to efficient carrier collection. Besides, the original topological properties of the 2D semi-metallic inclusions are also discussed. This comb-like heterostructure not only merges the superior optical properties of semiconductors with good transport properties of metallic materials, but also combines the high efficiency and tunability afforded by III-V inorganic bulk materials with the flexible management of nano-scale charge carriers usually offered by blends of organic materials. Physical properties of these novel hybrid heterostructures can be of great interest for energy harvesting, photonic, electronic or computing devices.

Loss assessment in random crystal polarity gallium phosphide microdisks grown on silicon.

III-V semiconductors grown on silicon recently appeared as a promising platform to decrease the cost of photonic components and circuits. For nonlinear optics, specific features of the III-V crystal arising from the growth on the nonpolar Si substrate and called antiphase domains (APDs) offer a unique way to engineer the second-order properties of the semiconductor compound. Here we demonstrate the fabrication of microdisk resonators at the interface between a gallium-phosphide layer and its silicon substrate. The analysis of the whispering gallery mode quality factors in the devices allows the quantitative assessment of losses induced by a controlled distribution of APDs in the GaP layer and demonstrates the relevance of such a platform for the development of polarity-engineered III-V nonlinear photonic devices on silicon.

Cathodoluminescence hyperspectral analysis of whispering gallery modes in active semiconductor wedge resonators.

Whispering gallery mode resonators are key devices for integrated photonics. Despite their generalization in fundamental and applied science, information on spatial confinement of light in these structures is mostly retrieved from purely spectral analysis. In this work, we present a detailed spectral and spatial characterization of whispering gallery modes in active semiconductor microdisk resonators by use of hyperspectral cathodoluminescence. By comparing our experimental findings to finite element simulations, we demonstrate that the combination of spectral and spatial measurements enables unique identification of the modes and even reveals specific features of the microresonator geometry, such as a wedge profile.