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Solution processed a-LaAlO3 gate dielectrics for their applications in thin film transistors employing metal oxide semiconducting channels

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Publication date2015
Original languageEnglish
EventEMRS 2015 - France, Lille, United Kingdom
Duration: 11/05/201515/05/2015

Conference

ConferenceEMRS 2015
CountryUnited Kingdom
CityLille
Period11/05/1515/05/15

Abstract

High-k dielectrics are extensively studied as alternatives to SiO2 as gate dielectrics for the next generation of field-effect transistors employing metal-oxide semiconducting channels. Amongst the wide range of high-k dielectrics LaAlO3 combines the advantages of the high permittivity of La2O3 with the chemical and thermal stability of Al2O3 and exhibits desirable chemical and electrical properties without the shortcomings of each individual material retaining at the same time a relatively high permittivity and large band gap. LaAlO3 films have been deposited by a variety of techniques including MBE, PLD, magnetron sputtering, sol-gel, ALD and MOCVD. Here, we report the deposition of a-LaAlO3 thin films as a function of the aluminium to lanthanum atomic ratio using spray pyrolysis, a simple and large-area-compatible deposition technique. The films were studied by means of atomic force microscopy, X-ray diffraction, impedance spectroscopy, UV–Visible absorption spectroscopy, spectroscopic ellipsometry, and field-effect measurements. Analyses reveal amorphous LaAlO3 that exhibit wide band gap (6.2 eV), low roughness (1.3 nm), high dielectric constant (17), and high breakdown voltage in excess of 3 MV/cm. Thin film transistors based on a-LaAlO3 gate dielectrics employing spray coated ZnO channels exhibit excellent electron transport characteristics with negligible hysteresis, high on/off current modulation ratio (>10^7) and electron mobility in excess of 12 cm^2 V−1 s−1.