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LaF3 as gate material in Schottky diodes for detection of HF and HCl in flue gases
2002 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The Swedish government and the Swedish parliament have decided to decrease dumping of waste to landfill. One solution is to combust more domestic waste. At the same time there are hard requirements from the government on the owner of the power plants, to measure and have control on the composition of the emissions in the flue gases from the combustion. Two important gases to measure are HF (Hydrofluoric acid) and HCl (Hydrochloric acid) and it is very interesting to develop price worthy measurement equipment that can measure those compounds. Vattenfall Utveckling AB and S- SENCE (Swedish Sensor Center), at the Department of Physics and Measurements Technology at Linköping University, have started a co-operation and are developing a sensor array that can measure important parameters in the flue gases in order to control small boilers. Experimental tests on Schottky diode sensors with LaF3 as gate material is the focus in this thesis. The main task was to investigate if there is possible to detect HF and HCl gas with the LaF3 as gate material and if the sensor can recognise and separate the gases from each other. The measurements show that it is possible to detect HF and HCl gas, although the responses are very small and unstable. This instability, which was mainly due to a phenomenon called series resistance, made it impossible to separate the gases from each other. Other parameters as dependence of temperature, test gas concentration, cross sensitivity to oxygen and response time has also been investigated. There were differences in response depending on temperature and concentration. Some of the sensors have cross sensitivity to oxygen and most of the response times were under one minute. The conclusion is that the sensors are too unstable due to series resistance to decide if they can detect HF and HCl in flue gases. More measurements have to be performed with more stable sensors in order to avoid the series resistance.

Place, publisher, year, edition, pages
Keyword [en]
Technology, Sensor, HF, HCl
Keyword [sv]
URN: urn:nbn:se:ltu:diva-46001ISRN: LTU-EX--02/360--SELocal ID: 3a5113a3-ef45-4587-b953-a40b3cc805a1OAI: diva2:1019309
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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