15:45 〜 16:00
▼ [19p-Z33-9] Band Engineering of Transparent Oxide Semiconductor ASnO3 (A = Ba, Ca, and Sr)
キーワード：optoelectronic properties, transparent oxide semiconductor, band engineering
Recently, La-doped ASnO3 (A = Ba, Sr, and Ca) films have been attracted increasing attention as the active channel of deep-ultraviolet (DUV) transparent thin-film transistors (TFTs), owing to their wide bandgap and high electrical conductivity. However, the effect of A-site substitution on the optoelectronic properties of ASnO3 has not been clarified in a detailed systematic study. Here we show that the optoelectronic properties of ASnO3 can be tuned systematically by changing the average size of A-site ions. We fabricated ASnO3 films heteroepitaxially on (001) LaAlO3 substrate and measured the optical absorption spectra and the electron transport properties of the resultant films. The lattice parameter almost linearly increased from 3.95 to 4.14 Å with increasing the average ionic radius of the A-site ion from 1.34 (Ca2+) to 1.61 Å (Ba2+). The optical bandgap gradually decreased from ~4.6 to ~3.6 eV with a small positive bowing. With increasing the lattice parameter, the electrical conductivity gradually increased from ~100 to ~103 S cm−1 due to a gradual increase in both carrier concentration and mobility. The present results are of significant importance for designing ASnO3-based transparent devices.