1,721,094 research outputs found
Localised tuneable composition single crystal silicon-germanium-on-insulator for low cost devices
No full textData for the paper Littlejohns, Callum, Dominguez Bucio, Thalia, Nedeljkovic, Milos, Mashanovich, Goran, Reed, Graham and Gardes, Frederic (2016) Localised tuneable composition single crystal silicon-germanium-on-insulator for low cost devices. Advances in Materials Science and Engineering</span
Silicon-germanium for photonic applications
No full textGermanium and silicon-germanium have become crucial materials in the silicon photonics field, enabling devices such as high speed photodetectors and high speed modulators to be realised.In order to fabricate efficient and cost effective silicon photonic devices, high quality epitaxial germanium and silicon-germanium growth on silicon, or silicon-on-insulator, is of the utmost importance.In this project, localised single crystal, defect free silicon-germanium on insulator islands have been grown using a rapid melt growth technique. Tailored tree-like structures have been used to modify the cooling rate of the structures during re-growth from the liquid phase. The resulting silicon-germanium composition profiles have been characterised using Raman spectroscopy.Using these tailored tree-like structures, uniform composition silicon- germanium strips have been grown, which is the first time this has been demonstrated using a rapid melt growth technique. Additionally, the ability to locally tune the composition of adjacent silicon-germanium strips has been shown. This enables the possibility of growing a whole range of uniform composition strips, using only a single growth step and a single anneal step, for, amongst others, wavelength division multiplexing applications.Epitaxial growth of germanium on silicon by plasma enhanced chemical vapour deposition has also been studied. Single crystal layers with a defect density of approximately 3.3x108 cm-2 and root mean square surface roughness of 3.5 nm have been demonstrated. It has also been shown that the defect density, surface roughness and crystallinity are all improved with a two minutes, 600 °C anneal.This material has been used to fabricate 12.5 Gbit/s, 0.1 A/W waveguide integrated, zero bias photodetectors for 1550 nm silicon photonics applications, and also, germanium-on-silicon waveguides for mid-infrared silicon photonics applications
Education and training of silicon photonics engineers and technicians
No full textAt the University of Southampton, we have established an educational photonics pathway in which we teach our undergraduate and postgraduate students the fundamentals of silicon photonics. We have designed silicon photonics laboratories, for both simulation and characterization, where our students have opportunities to design their chips and characterize them. Our assessment strategy aims to improve students’ self-assessment and feedback skills. The material we have developed is also being used for training our technicians and PhD students
Silicon diffusion engineering in rapid melt growth of silicon-germanium on insulator
Full text linkIn this paper we focus on developing an efficient method to obtain a crystalline SiGe layer on top of an insulator. The method is aimed at enabling the fabrication of different concentration of crystalline SiGe alloy through structure engineering. This technique could enable the alloy composition to be different by design across a single wafer by using a single Germanium deposition step
Micro-transfer printed InGaAs photodetector on SOI platform
No full textTransfer-printed InGaAs photodetectors are integrated on SOI by evanescent, grating and edge coupling, exhibiting responsivities of 0.7, 0.38 and 0.15 A/W, with dark currents of 48,47 and 400 nA at 0.6 V reverse bias respectively. </p
Application of adiabaticity map: highly efficient coupling from optical fibers to silicon waveguides by adiabatic mode evolution
No full textEfficient coupling of light from an optical fiber to silicon waveguides is a challenging task in integrated photonics. Couplers based on adiabatic mode evolution have the advantages of high bandwidth and low loss but are often accompanied by longer device lengths. In this paper, we introduce the concept of adiabaticity map and optimize the coupling between an optical fiber and Si waveguides by selecting routes on the map that minimize unwanted mode coupling. The map clearly indicates areas in mode evolution where supermode coupling is large and identifies optimal routes for efficient mode evolution. Optimized interaction length and widths are obtained from the adiabaticity map. We obtain highly efficient coupling (96%) with large bandwidth (1-dB bandwidth 280 nm) and misalignment tolerance (⪆90 nm lateral misalignment range for 1-dB excess losses) for the TE polarization.Dynamics of Micro and Nano System
SiGe bandgap tuning for high speed Eam
No full textWe report bandgap engineering of Ge rich SiGe rib waveguides between 1550 nm and 1580 nm through an annealing process. The insertion loss of the material (transmission spectrum) is analysed between 1520 nm and 1600 nm. The experimental data are elaborated by implementing the Tauc Method analysis, and the material bandgap estimation is calculated. A maximum blue shift of 38 nm, with an overall reduction of Si content, suggests that the diffusion of Si in the Ge seed layer during anneal improves the homogeneity of the growth layer. The proposed technique provides a path for tailoring the operational wavelength of devices such as electro-absorption modulators, realized on an SOI platform
Laser-assisted material composition engineering of SiGe planar waveguides
No full textWe report the compositional engineering of silicon-germanium planar microstructures through laser processing. The effects of the laser treatment are assessed through microscope imaging and Raman spectroscopy. Our results reveal that the laser-exposed regions display a significant change in the material composition
Dataset for 'A Si Optical Modulator based on Fano-like Resonance'
No full textThis dataset supports the publication: H. Du, W. Zhang, W. Cao, D. J. Thomson, C. G. Littlejohns, X. Yan, D. T. Tran, M. Banakar, G. T. Reed (2021) 'A Si Optical Modulator based on Fano-like Resonance' published in IEEE Photonics Technology Letters
In this work, we present an experimental demonstration of a carrier depletion type Si optical modulator using Fano-like resonance, which is the first of its kind in the literature. The Fano-like resonance is obtained by weak coupling between two optical resonators in the prototype device and the PN junction is designed for carrier-depletion type electro-refractive modulation. 20 Gb/s on-off keying (OOK) is obtained in experiments on the prototype device. </span
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