Use this URL to cite or link to this record in EThOS:
Title: Gas sensors using carbon nanotubes
Author: Haque, M. S.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
A novel approach has been adopted for in-situ growth of CNTs on CMOS Silicon on Insulator (SOI) devices. The growth and deposition of CNTs on SOI CMOS has been successfully implemented at high temperature (>700°C) using tungsten as an interconnect. A detailed study of the nanotubes growth dependence on a number of parameters has been carried out on fully processed SOI CMOS substrates. A novel growth process of depositing CNTs using the very low power CMOS microhotplate acting as the thermal source has also been carried out. One of the key advantages of this process is the confinement of high temperature to the heater region only during the CNT growth, thereby, keeping the electronic circuitry unaffected. The results of the growth were highly repeatable with no degradation of the CMOS devices. High quality multi walled CNTs were locally grown, self-aligned onto the pre-formed sensing metal interdigitated electrodes. A low temperature process (<450°C) for single walled and multi walled CNTs was also developed using a hot filament stage. This process is suitable for devices with aluminium interconnect and is CMOS compatible. The locally growth CNTs on the sensor devices were tested with NO2 extensively and showed response at room temperature which was an improvement on the present gas sensing technologies. The sensor was found to offer reasonable sensitivity to 100 ppb of NO2 and faster chemical response time at elevated temperatures (tens of seconds). The smart CNT micro-sensor also showed responses to ammonia, methanol and ethanol. The ultra-low power consumption of the hotplates on ultra-thin CMOS compatible membranes and the growth of CNTs on multi-chips at the same time, in parallel, show great potential for high volume manufacturability and is a potential way forward for the next generation nanostructured material sensors.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available