미스트 기상 화학 증착법을 이용한 산화 아연 주석 반도체, 알루미나 절연체의 연구.

Abstract

Zinc tin oxide (Zn-Sn-O or ZTO) semiconductor layers were synthesized based on solution processes, of which one type involves the conventional spin coating method and the other is grown by mist chemical vapor deposition (Mist-CVD). Liquid precursor solutions are used in each case, with tin chloride and zinc chloride (1:1) as solutes in solvent mixtures of acetone and deionized water. Mist-CVD ZTO films are mostly polycrystalline, while those synthesized by spin-coating are amorphous. Thin-film transistors based on Mist-CVD ZTO active layers exhibit excellent electron transport properties with a saturation mobility of 14.6 cm2/Vs, which is superior to that (6.88cm2/Vs) of their spin-coated counterparts. X-ray photoelectron spectroscopy (XPS) scans suggest that the Mist-CVD ZTO films contain relatively smaller amounts of oxygen vacancies, hence lower free carrier concentrations. The enhanced electron mobility of Mist-CVD ZTO is thus anticipated to be strongly correlated to the electronic band structure, which is examined by X-ray absorption near-edge structure (XANES) analyses. Additionally, Aluminum Oxide (AlOx) gate insulator layers were grown by mist chemical vapor deposition, spin-coating. AlOx thin films were formed by mist-chemical vapor deposition, spin-coating from aluminum acetylacetonate (Al(acac)3) dissolved in aqueous solvents (acetone and water) at growth annealing, temperatures of 250 - 350 °C. TGA-DSC data of aluminum acetylacetonate solution showed two-step evaporation with ~4 at% residue. AlOx thin films were deposited with N2 purge and Aluminum solution and growth rate of 7.5 - 13.3nm/min was achieved at 250 - 350 °C. AlOx thin films deposited at temperatures below 350 °C showed 3-5 at% residual carbon levels but AlOx thin films grown at 350 °C exhibited 1-2 at% residual carbon (C) levels. Also, the potential insulator properties were obtained by the formation of pure Al–O components at the highest growth temperature. Consequently, Electrical properties of AlOx films showed the dielectric constant(κ) of ~7.0, breakdown field of ~9 (MV/cm) and current density of ~ 8.2E-10 (A/cm2) at 350 °C.