Solution-processed wafer-scale indium selenide semiconductor thin films with high mobilities

Solution-processed two-dimensional semiconductors could be used to create electronic devices on large scales and at low cost. However, the electronic performance of devices based on such materials is typically below that of devices based on materials grown via high-temperature chemical vapour deposition. Here we report the fabrication of indium selenide (InSe) semiconductor thin films using a colloidal solution of monolayer nanosheets (monolayer purity more than 98%). The InSe thin films are assembled on 4-inch wafers with conformal and intimate van der Waals contacts between the monolayer building blocks. We use the solution-processed films to fabricate InSe transistors that exhibit electron mobilities of 90–120 cm 2  V −1  s −1 , current on/off ratios of up to 10 7 and a small current hysteresis. We also show that InSe transistors with oxide encapsulation can remain stable in air for 3 months.