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Adnan Hammud

Publications and source records attributed to Adnan Hammud.

2 recordsLinked to original sources

Tunable Light Emission from GaAsP and GaInP Islands Grown on Silicon (001) Nanotips Wafer

In this work, we present the monolithic integration of GaAsP and GaInP islands, selectively grown on a CMOS-compatible Si nanotip wafer using gas-source molecular beam epitaxy via a nanoheteroepitaxy approach. These alloys span a wide electronic bandgap range, from infrared to green; making them highly attractive for optoelectronic applications in silicon photonics. In addition, the nanoheteroepitaxy method enables the growth of various alloy combinations without the need for a lattice-matched substrate. We discuss the epitaxial challenges involved, particularly the balance between growth selectivity and alloy miscibility. Despite these challenges, our work demonstrates a promising and scalable route toward tunable light sources and detectors monolithically integrated on silicon, contributing to the development of compact and efficient photonic components for next-generation silicon-based technologies.

physics.optics

Scattering near-field optical microscopy at 1-nm resolution using ultralow tip oscillation amplitudes

Scattering-type scanning near-field optical microscopy (s-SNOM) allows for the observation of the optical response of material surfaces with a resolution far below the diffraction limit. Based on amplitude-modulation atomic force microscopy (AFM) with typical tapping amplitudes of tens of nanometers, a spatial resolution of 10-100 nm is routinely achieved in s-SNOM. However, optical imaging and spectroscopy of atomic-scale structures remain a substantial challenge. Here, we developed ultralow tip oscillation amplitude s-SNOM (ULA-SNOM), where the ultra-confined field localized at a 1-nm-scale gap between a plasmonic tip and sample is combined with frequency-modulation (non-contact) AFM in a stable cryogenic ultrahigh vacuum environment. Using a silver tip under visible laser illumination with a constant 1-nm amplitude oscillation, we obtain a material-contrast image of silicon islands on a silver surface with 1-nm lateral resolution, which surpasses the conventional limits of s-SNOM. ULA-SNOM paves the way for the acquisition of optical information from atomic-scale structures, such as single photo-active defects and molecules.

physics.optics