[19p-Z33-1~16] 21.1 Joint Session K "Wide bandgap oxide semiconductor materials and devices"

▼ [19p-Z33-9] Band Engineering of Transparent Oxide Semiconductor ASnO₃ (A = Ba, Ca, and Sr)

〇(DC)Mian Wei¹, Hai Jun Cho^1,2, Hiromichi Ohta^1,2 (1.IST-Hokkaido Univ., 2.RIES-Hokkaido Univ.)

Keywords: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.