Transforming insulating rutile single crystal into a fully ordered nanometer-thick transparent semiconductor

Rutile single crystals treated with ion-beam preferential etching (IBPE) are investigated with electrical transport and transmission electron microscopy. The initially insulating single crystals show the formation of an oxygen vacancy-rich, highly ordered, thin conducting layer, below a crystalline rutile TiO₂ surface layer. Carrier concentrations of 10¹⁹ cm ^-3 and very high mobilities of the order of 300 cm2 V^-1 s^-1 are observed in the nanolayers. The observations indicate that rutile single crystals can be effectively transformed into controlled conducting material using IBPE for creating a new breakthrough in transparent conducting media.