Unexpected Aspects of Strain Relaxation and Compensation in InGaAs Metamorphic Structures Grown by MOVPE

We present a selection of stack designs for MOVPE grown In_<i>x</i>Ga_1–<i>x</i>As metamorphic buffer layers following various convex-down compositional continuous gradients of the In content, showing that defect generation and strain can be managed in a variety of ways, some rather unexpected (and unreported). Indeed, we observe that it is possible to grow surprisingly thick tensile strained layers on metamorphic substrates, without significant relaxation and defect generation. We believe our findings give significant insights to the investigation of strain, relaxation, and defect distribution in metamorphic buffer design, so to obtain properly engineered/tailored structures (the most successful ones already finding applications in device growth)

Hot-Electron Injection in Au Nanorod–ZnO Nanowire Hybrid Device for Near-Infrared Photodetection

In this Letter, we present a new class of near-infrared photodetectors comprising Au nanorods–ZnO nanowire hybrid systems. Fabricated hybrid FET devices showed a large photoresponse under radiation wavelengths between 650 and 850 nm, accompanied by an “ultrafast” transient with a time scale of 250 ms, more than 1 order of magnitude faster than the ZnO response under radiation above band gap. The generated photocurrent is ascribed to plasmonic-mediated generation of hot electrons at the metal–semiconductor Schottky barrier. In the presented architecture, Au-nanorod-localized surface plasmons were used as active elements for generating and injecting hot electrons into the wide band gap ZnO nanowire, functioning as a passive component for charge collection. A detailed investigation of the hot electron generation and injection processes is discussed to explain the improved and extended performance of the hybrid device. The quantum efficiency measured at 650 nm was calculated to be approximately 3%, more than 30 times larger than values reported for equivalent metal/semiconductor planar photodetectors. The presented work is extremely promising for further development of novel miniaturized, tunable photodetectors and for highly efficient plasmonic energy conversion devices

Supplementary document for 100 Gbps PAM4 ultra-thin photodetectors integrated on SOI platform by micro transfer printing - 6642949.pdf

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Supplementary document for 100 Gbps PAM4 ultra-thin photodetectors integrated on SOI platform by micro transfer printing - 6635941.pdf

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Direct visualization of phase-matched efficient second harmonic and broadband sum frequency generation in hybrid plasmonic nanostructures

Second harmonic generation and sum frequency generation (SHG and SFG) provide effective means to realize coherent light at desired frequencies when lasing is not easily achievable. They have found applications from sensing to quantum optics and are of particular interest for integrated photonics at communication wavelengths. Decreasing the footprints of nonlinear components while maintaining their high up-conversion efficiency remains a challenge in the miniaturization of integrated photonics. Here we explore lithographically defined AlGaInP nano (micro)structures/ Al2O3/Ag as a versatile platform to achieve efficient SHG/SFG in both waveguide and resonant cavity configurations in both narrow- and broadband infrared (IR) wavelength regimes (1300–1600nm). The effective excitation of highly confined hybrid plasmonic modes at fundamental wavelengths allows efficient SHG/SFG to be achieved in a waveguide of a cross-section of 113nm×250nm, with a mode area on the deep subwavelength scale (λ2/135) at fundamental wavelengths. Remarkably, we demonstrate direct visualization of SHG/SFG phase-matching evolution in the waveguides. This together with mode analysis highlights the origin of the improved SHG/SFG efficiency. We also demonstrate strongly enhanced SFG with a broadband IR source by exploiting multiple coherent SFG processes on 1µm diameter AlGaInP disks/Al2O3/Ag with a conversion efficiency of 14.8%MW−1 which is five times the SHG value using the narrowband IR source. In both configurations, the hybrid plasmonic structures exhibit >1000 enhancement in the nonlinear conversion efficiency compared to their photonic counterparts. Our results manifest the potential of developing suchnanoscale hybrid plasmonic devices for state-of-the-art on-chip nonlinear optics applications