Thomas Swan Research Articles

Black Swan Graphene collaborates with Hubron, Thomas Swan & Roger Bullivant on graphene-enhanced masterbatches & concrete admixtures

Black Swan Graphene collaborates with Hubron, Thomas Swan & Roger Bullivant on graphene-enhanced masterbatches & concrete admixtures

Thomas Swan forms graphene joint venture

Thomas Swan forms graphene joint venture

Thomas Swan forms Black Swan graphene joint venture with Mason Graphite

Thomas Swan forms Black Swan graphene joint venture with Mason Graphite

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2021, 99 (24), p 17June 28, 2021Cite this:C&EN 99, 24, 17AbstractDow and Shell will receive $4.2 million in funding from the Dutch government toward their work in electrically heated ethylene steam-cracking furnaces. The companies say they are evaluating the construction of a pilot plant by 2025, “subject to investment support.” Tosoh will spend $90 million to renovate and expand its Tokyo Research Center in Ayase, Japan. The firm says the project, set for completion in 2026, will include a building for advanced organic materials research. Johnson Matthey , Thomas Swan, and the UK technology agency CPI are investigating ways to increase the performance of Johnson Matthey’s lithium-ion battery materials using carbon nanotubes and graphene nanoplatelets. The project will receive funding from the UK government’s Faraday Battery Challenge. Invista plans to build a nylon 6,6 technology application center in Shanghai at a cost of $15 million. The center will undertake analytical and mechanical testing of engineering polymers for markets including automotiveView: PDF | Full Text HTML

Graphene targeted at concrete market

The UK specialty chemical maker Thomas Swan will supply its graphene nanoplatelets to Concrene, a University of Exeter spin-off that wants to lower the carbon footprint of concrete production. The start-up says strengthening concrete with graphene allows builders to use less of it, thus reducing carbon emissions. According to the partners, concrete production is responsible for 8% of the world’s carbon emissions.

Bolder appoints Thomas Swan to sell its recovered carbon black

Bolder appoints Thomas Swan to sell its recovered carbon black

Enhancing coatings for metal packaging

Coatings firm AkzoNobel, specialty chemical maker Thomas Swan, and packaging firm Crown Packaging Manufacturing have formed a U.K. consortium to develop raw materials and formulations for coatings ...

Thomas Swan links with graphene center

Thomas Swan links with graphene center

Thomas Swan Teams Up On Graphene Projects

Thomas Swan Teams Up On Graphene Projects

In-situ wafer bowing measurements of GaN grown on Si (111) substrate by reflectivity mapping in metal organic chemical vapor deposition system**Project supported by the National Natural Science Foundation of China (Grant Nos. 61274039 and 51177175), the National Basic Research Program of China (Grant No. 2011CB301903), the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20110171110021), the International

In this work, the wafer bowing during growth can be in-situ measured by a reflectivity mapping method in the 3×2″ Thomas Swan close coupled showerhead metal organic chemical vapor deposition (MOCVD) system. The reflectivity mapping method is usually used to measure the film thickness and growth rate. The wafer bowing caused by stresses (tensile and compressive) during the epitaxial growth leads to a temperature variation at different positions on the wafer, and the lower growth temperature leads to a faster growth rate and vice versa. Therefore, the wafer bowing can be measured by analyzing the discrepancy of growth rates at different positions on the wafer. Furthermore, the wafer bowings were confirmed by the ex-situ wafer bowing measurement. High-resistivity and low-resistivity Si substrates were used for epitaxial growth. In comparison with low-resistivity Si substrate, GaN grown on high-resistivity substrate shows a larger wafer bowing caused by the highly compressive stress introduced by compositionally graded AlGaN buffer layer. This transition of wafer bowing can be clearly in-situ measured by using the reflectivity mapping method.

Correlation of Selected Problems During Gan Movpe Epitaxy on si Substrates with in–Situ Interferometer Observation

Abstract In this paper, selected problems occurring during GaN epitaxy on Si substrates are correlated with in-situ interferometer observations based on structures fabricated using 3×2” Thomas Swan Close Coupled Showerhead MOVPE system. Samples were epitaxially grown on highly resistive (> 500cm) p-type 2” silicon substrates. The growth was observed using an interferometer acquiring reflectance traces in-situ. To avoid issues that are shown in this paper, different approaches of the so-called buffer layer were used by depositing them on Si before the growth of GaN. Different material qualities of grown GaN layers were obtained by variation in films constituting the buffer layer grown before the desirable GaN film. The study shows the evolution of the grown samples, improvement of various parameters and also gradual reduction of material issues discussed in this paper. Improvement in GaN layer was mainly observed by SEM characterization and studying the growth mechanisms through observation of reflectance traces obtained in-situ.

Nonionic Electrophoretic Sorting of SWCNTs into Metallic and Semiconducting Tubes

ABSTRACTWe present our preliminary results on a novel technique to electrophoretically sort singlewall carbon nanotubes into metallic and semiconducting tubes using a free-solution nonionic surfactant in a homemade electrophoretic vertical cell. The technique is used to sort purified commercial product SWCNTs, (Thomas Swan Elicarb) into metallic and semiconducting tubes. In contrast to onventional electrophoresis techniques, which takes more than 24 hours to obtain efficient separation, our approach takes ∼ 6 hours to achieve efficient separation, which reduces the separation time by four fold. Characterization of the sorted tubes with micro-Raman spectroscopy analysis shows very strong enrichment of both metallic and semiconducting tubes.

Numerical studies on flow and thermal fields in MOCVD reactor

A systematic study has been performed to investigate the flow and thermal patterns of vertical rotating Thomas Swan MOCVD reactor at low pressure, using 2-D dynamic modeling. By varying and calculating the several important process parameters of the reactor, the optimized conditions of the uniform distributions of velocity and temperature profiles in steady state have been obtained. Then, time-dependent models with the step response perturbation of the total gas rate can help identify the visual transient behavior inside the reactor and analyze the mechanism of delay time, relaxation oscillation and pulsative oscillation. These results are beneficial to the process parameter optimization and geometrical configuration design of the MOCVD reactor.

Thomas Swan Matheson

Thomas Swan Matheson (“Tom”) was one of the last truly general surgeons, with a special interest in gastrointestinal surgery. He worked at a time when medical professionals managed, as well...

Investigation of ZnO nanopillars fabrication in a new Thomas Swan close coupled showerhead MOCVD reactor

Self-organized ZnO nanopillars were grown on a-plane Al2O3 in a vertical MOCVD reactor using diethylzinc and N2O as precursors. This is the very first Thomas Swan reactor that is specially designed for the growth of ZnO and GaN. The influence of different growth parameters including growth time, VI/II-ratio, substrate temperature and reactor pressure on the shape of the nanostructures is investigated by field emission scanning electron microscopy. An explanation for the formation of nanopillars is given resulting in high substrate temperatures and low VI/II-ratios for the best results. It is shown that the density, length and diameter can be controlled choosing appropriate growth parameters.

Strain-balanced MQW pin solar cells grown using a robot-loading showerhead reactor

A touch-screen controlled, robot-loading system for the Thomas Swan 7×2 flip-top showerhead reactor has been developed. The reactor has been configured for the growth of GaAs and InP materials and has been used to prepare strain-balanced MQW (SBMQW) pin solar cell material on GaAs substrates. Both material characterisation and solar cell performance for SBMQW pin cells are described.

High current gain InGaN/GaN HBTs with 300°C operating temperature

Material growth and device fabrication: The materials used in this study are grown in a Thomas Swan close-coupled showerhead (CCS) metal organic chemical vapour deposition (MOCVD) reactor with a 7 � 2 inch diameter wafer capacity. Trimethylgallium (TMGa), trimethylindium (TMIn), and high-purity ammonia (NH3 )a re used as the primary sources, while disilane (Si2H6) and bis-cyclopenta- dienylmagnesium (Cp2Mg) are the n-type and p-type dopant sources, respectively. All devices are grown on a 2.5 mm-thick high- temperature (Tg ¼ 1050 � C) GaN layer, which is grown with an � 20 nm low-temperature (Tg ¼ 550 � C) GaN buffer layer on a (0001) sapphire substrate. The layer structure of the InGaN=GaN HBT used in this study is shown in Table 1, and includes compositional grading in the emitter to eliminate any conduction band spikes, as well as to enhance the valence band barrier to holes. The graded region between the base and collector is n-type doped as a means of compensating polarisation charges that arise from compositional grading. The indium mole fraction was determined using X-ray diffraction rocking curve measurements. The hole concentration in the p þ InGaN base layer, as determined from Hall measurements, was found to be 2.5 � 10 18 cm � 3 , with a mobility of 3c m 2 =V-s at room temperature. SIMS profiles of this wafer show a Mg concentration of (Mg) � 3 � 10 19 cm � 3 . It should be noted that the base layer is designed with a slight reverse grade, with 3% indium mole fraction at the collector side of the base, graded to 4% at the emitter, in order to suppress defect formation and improve the epitaxial material quality. This grade is in the direction opposite to that desired to increase current gain.

Effect of V/III ratio in AlN and AlGaN MOVPE

Experimental studies of AlN and AlGaN deposition in a 3×2″ Thomas Swan close-coupled showerhead reactor have revealed the effect of growth rate reduction at enhanced ammonia and group-III flow rates. Detailed modeling was made of gas-phase chemistry, taking into account parasitic reactions as well as formation and growth of nanoparticles. The kinetics of interactions between trimethylaluminium (TMAl) and ammonia explains the presence of nanoparticles at high ammonia/TMAl flow rates, and their absence at low ammonia/high TMAl or high ammonia/low TMAl flow rates. It is shown that the growth efficiency can be increased by reduction of the carrier gas flow rate at relatively low V/III ratios, or by total reactor pressure decrease.

Focus on Aixtron

At a financial level, Aixtron on Dow Jones wires shows “Shares continue upward drive from Wednesday, profiting from the positive sentiment in the semiconductor sector.” “The share broke an important resistance at EUR2.80 yesterday,” trader says. “Next resistance seen at EUR3.25, then EUR3.31. Shares +3.8% at EUR3.03.” Organisationally, the company news is the establishment of a European organisation, headed by Frank Schulte (who set up Aixtron's Japanese subisidiary) responsible for sales, service and spares for Thomas Swan, Epigress and Genus, and also enfolding Israel and Russia. Bill Elder is now on the executive board as chairman of Aixtron's silicon business. III-Vs Review interviews president and CEO, Paul Hyland, and director of marketing, Dr Rainer Beccard.

Mr Thomas Swan (19 Oct 1929–15 Dec 2004)

Mr Thomas Swan (19 Oct 1929–15 Dec 2004)