Optoelectronic properties of transparent oxide semiconductor ASnO₃ (A = Ba, Sr, and Ca) epitaxial films and thin film transistors

The importance of transparent oxide semiconductors is growing immensely due to their unprecedented dual properties: high electrical conductivity and optical transparency. They have been widely used in many transparent electronics devices due to their excellent electronic properties. In this Review, we discuss our recent research progresses on transparent ASnO₃ (A = Ba, Sr, and Ca)-based thin films and thin film transistors (TFT). Here, we have explored the underlying materials physics through the investigation of fundamental properties such as effective mass, effective channel thickness, carrier mobility, electrical characteristics, and optical properties. High Hall mobility and wide bandgap are the key deciding parameters to consider when choosing ASnO₃ for transparent electronic applications. Thus, carrier mobility improvisation was also carried out via modifying thin film preparation conditions such as using the highly oxidative atmosphere, vacuum annealing, and increasing the film thickness. Furthermore, we clarified the operating mechanism of BaSnO₃-SrSnO₃ solid solution-based TFTs and succeeded in fabricating the deep-UV La-doped SrSnO₃ TFTs, which has great potential in biological applications. We have also demonstrated that the optoelectronic properties ASnO₃ may be controlled by changing the A-site, which is consistent with expectations from the lattice parameter changes. This Review provides better options for designing ASnO₃-based transparent devices in future.