Abstract. Un-doped ZnO and MgZnO thin films were deposited on c-plane sapphire substrates by molecular-beam epitaxy (MBE) and subsequently annealed in hydrogen ambient at 200–500 oC with a step of 100 oC. Halleffect measurements show that annealing temperature has great effect on the electrical property of both ZnO and MgZnO films. The electron concentration of both ZnO and MgZnO films in…