We report on the growth and characterization of Na-doped non polar ZnO thin films, which have been prepared on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The effects of Na contents On structural, morphological, electrical, and optical properties of Na-doped non-polar m-plane ZnO films are investigated. All the doped thin films have uniform m-plane orientation, which benefit from Na-doping. Na content plays a key role in determining the conduction of the ZnO films. An optimized result with a hole concentration of 5.3 x 10(16) cm(-3), a Hall mobility of 0.22 cm(2) V-1 s(-1), and a resistivity of 530 Omega cm is achieved at beam equivalent pressure of the elemental Na source of 8.7 x 10(-9) Torr, and the films are electrically stable over several months. (C) 2014 Elsevier B.V. All rights reserved.