High electrical conducting deep-ultraviolet- transparent oxide semiconductor La-doped SrSnO_3 exceeding ~3000 S cm~(-1)

摘要

La-doped SrSnO3 (LSSO) is known as one of the deep-ultraviolet (DUV)-transparent conducting oxides with an energy bandgap of similar to 4.6 eV. Since LSSO can be grown heteroepitaxially on more wide bandgap substrates such as MgO (E-g similar to 7.8 eV), LSSO is considered to be a good candidate for a DUV-transparent electrode. However, the electrical conductivity of LSSO films is below 1000 S cm(-1), most likely due to the low solubility of the La ion in the LSSO lattice. Here, we report that high electrically conducting (>3000 S cm(-1)) LSSO thin films with an energy bandgap of similar to 4.6 eV can be fabricated by pulsed laser deposition on a MgO substrate followed by a simple annealing in vacuum. From the X-ray diffraction and the scanning transmission electron microscopy analyses, we found that lateral grain growth occurred during the annealing, which improved the activation rate of the La ion, leading to a significant improvement of the carrier concentration (3.26 x 10(20) cm(-3)) and Hall mobility (55.8 cm(2) V-1 s(-1)). The present DUV-transparent oxide semiconductor would be useful as a transparent electrode for developing optoelectronic devices, which transmit and/or emit DUV-light.