Transparent conducting zinc nitride films

Highly conducting Zn3N2 thin films were reactively sputtered on unheated glass. Well-crystallized polycrystalline films were obtained even though the films were deposited at a low temperature. Nitrogen-deficient Zn3N2 films exhibited n-type conductivity and resistivities of the order of 10(-3) Omega cm. All the obtained Zn3N2 films had sufficiently high electron mobilities in the range of 30 to 66 cm(2) V-1 s(-1). Such high mobilities probably originate from the small electron effective mass of 0.27 m(0) (where m(0) denotes free electron mass), which was confirmed by infrared reflectance measurements. Furthermore, we found that intentional oxygen doping reduced the resistivities of Zn3N2 thin films to 8.9 x 10(-4) Omega cm. Optical measurements revealed that the direct optical band gap of the Zn3N2 films was in the range of 2.9-3.1 eV. These results suggest that impurity-doped Zn3N2 is a candidate for a new nitride-based transparent conductor. (C) 2014 The Japan Society of Applied Physics