Recent progress in transparent oxide semiconductors: Materials and device application

This paper reviews our recent research progress on new transparent conductive oxide (TCO) materials and electronic and optoelectronic devices based on these materials. First, described are the materials including p-type materials, deep-UV transparent TCO(β-Ga2O3), epitaxially grown ITO with atomically flat surface, transparent electrochromic oxide (NbO2F), amorphous TCOs, and nanoporous semiconductor 12CaO · 7Al2O3. Second, presented are TCO-based electronic/optoelectronic devices realized to date, UV/blue LED and UV-sensors based on transparent pn junction and high performance transparent TFT using n-type TCO as an n-channel. Finally, unique optoelectronic properties (p-type degenerate conduction, transfer doping of carriers, RT-stable exciton, and large optical nonlinearity) originating from 2D-electronic nature in p-type layered oxychalcogenides are summarized along with the fabrication method of epitaxial thin films of these materials.