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Controlled Deposition Of Semiconducting Carbon Nanotube Thin Films And Fabrication Of Highperformance Transistor Arrays

Posted on:2022-03-03Degree:MasterType:Thesis
Country:ChinaCandidate:Z YangFull Text:PDF
GTID:2481306536990069Subject:Materials science
Abstract/Summary:PDF Full Text Request
Carbon nanotubes(CNTs)have various applications due to their excellent properties.For example,single-walled carbon nanotubes(SWNTs)are widely used in integrated circuits due to their high carrier mobility and long mean free path.However,it is very difficult to determine the specific positions of individual SWNTs,which indues a great challenge for large-scale production of devices based on individual SWNTs.SWNT thin films not only remain the pristine micro-properties of individual SWNTs,but also possess the unique features of two-dimensional materials,and thus show a broad application prospect.This thesis focuses on controllable solution-based deposition of high quality semiconducting SWNT thin films and fabrication of high-performance thin-film transistor arrays.The main research contents are as follows:High-quality semiconducting SWNT thin films were deposited on Si/Si O2 substrate by a solution-based process.The substrates were functionalized by poly-lysine(PLL)and 3-minopropyltriethoxysilane(APTES),respectively;both the deposition process and morphology of the thin films have been systematically studied.Subsequently,high-performance thin-film transistor arrays were fabricated by using the deposited SWNT thin films as the channel layer,and their electrical properties were tested with a large quantity of devices.The effects of the thin films deposited on the substrates functionalized by two different molecules on the device performance were analyzed.The experimential results showed that the PLL modified Si/Si O2 substrate remarably benefits the SWNT thin film deposition,and the fabricated thin-film transistors show better device performance.Before and after the photoresist on the SWNT thin-film channel was removed,the transistors show different transport performance.When the carbon nanotube channel was covered by the photoresist,the thin-film transistors showed an ambipolar transport behavior;however,after the photoresist was removed,the transistors exposed to the ambient atmosphere transformed to the unipolar p type characteristics,and the recorded on-state current was 3.52 times larger than that of the devices before the photoresist was removed.Two series of SWNT thin films were deposited using semiconducting nanotube solutions with different purities.The effects of deposition time and the purity of semiconducting SWNTs on the film deposition process the morphology were studied,thin-film transistor arrays were consequently fabricated.The performance parameters of the transistor arrays with different nanotube densities and the purity of semiconducting SWNTs have been systematically compared and analysed.The results showed that transistor arrays,which were fabricated based on SWNT thin films deposited using 99.9%semiconducting nanotube solution with a deposition time of 50 min,possess the optimized performance,the measured current on/off ratio was as high as 106,and the field-effect mobility reached 26cm2 V-1 s-1.
Keywords/Search Tags:semiconducting SWNT thin films, solution-based deposition, purity of the semiconducting SWNTs, transistor arrays, field-effect mobility, current on/off ratio
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