Transparent thin film oxide semiconductor material with highest recorded conductivity for its class.A team led by researchers at the University of Minnesota has developed a new transparent thin film oxide semiconductor material that offers the highest recorded conductivity for its class. The nano-scale material could lead to smaller, quicker and more powerful electronics as well as more efficient solar cells.
As reported in Nature Communications [Prakash et al. Nat. Commun. (2017) DOI: 10.1038/ncomms15167], its high conductivity makes the sustainable material unique, as it helps electronics conduct more electricity and become more powerful. Based on cheaper and more abundant elements than the indium-based transparent conductors commonly used, it also has a wide bandgap – so light can pass easily through, making it optically transparent. These properties make it ideal for conducting films that can be used in many electronic devices, such as high-powered electronics, transparent displays, touchscreens and even solar cells.
The researchers developed their conducting thin film using a novel synthesis method in which they grew a barium stannate (BaSnO3) thin film and replaced the tin source with a chemical precursor with properties that can enhance chemical reactivity and improve the metal oxide formation process. They showed that BaSnO3, if synthesized with low defect density, could offer much better properties, as well as showing what limits the conductivity in such materials and how to increase the conductivity. The approach uses a combination of solid (for Ba) and chemical sources (for Sn) so that the material takes advantage of both thermodynamics and chemistry, with the materials being of extremely high quality while being scalable.
“Even though this material has the highest conductivity within the same materials class, there is much room for improvement in addition, to the outstanding potential for discovering new physics if we decrease the defects”Bharat Jalan
The team, who were among the first to recognize the potential of such thin films as transparent conductors, found the process allowed them to create the material with control over thickness, composition, and defect concentration, while the structurally superior quality with improved defect concentration meant they could observe high conductivity in the material. Also, as lead researcher Bharat Jalan said, “Even though this material has the highest conductivity within the same materials class, there is much room for improvement in addition, to the outstanding potential for discovering new physics if we decrease the defects.”
As thin films are key to integration with micro- or nano - fabrication technology, the insights provided here will help direct future research towards minimizing the defects and improving the material’s properties. It is hoped the process will be effective for other material systems where the element is hard to oxidize, and the team will continue to develop their approach and investigate materials with an atomic level of control to better understand the role of specific defects.