Researchers working at Dongguk University, Seoul have found thinning layers of copper iodide can make transparent, high-mobility p-channel transistors that may be suitable for displays and other optoelectronic systems.
The team led by Professor Yong-Young Noh opted for the material for two reasons: "The naturally abundant and environmentally friendly constitutional elements of CuI make it more appropriate for large-scale printed transparent electronics. More importantly, CuI has a higher hole mobility than other p-type oxide-based semiconductors."
The issue with CuI up to now is that its hole mobility is so good that it makes an ineffective semiconductor – the gate cannot influence the channel enough to stem the flow of electrons. Conventional solution-based processing to apply the films also calls for an annealing step that consumes more energy and time than is desirable and which could affect other devices on the substrate.
By thinning the CuI to around 5nm, the mobility falls far enough to make use in transistors practical.