Growth and characterization of single crystalline Ga-doped ZnO films using rf magnetron sputtering

In this article it is shown that high quality single crystalline Ga-doped ZnO (GZO) films could be achieved on ac-plane sapphire using conventional rf magnetron sputtering. High-resolution x-ray diffractometry, transmission electron microscopy (TEM), and scanning electron microscopy investigations clearly confirmed that the GZO films with low Ga doping levels up to 1wt% were of high quality single crystal, which is featured by the (0002) rocking curve as narrow as 0.14°, symmetric six poles in pole figure, sharply defined spot pattern in the TEM diffraction diagram of the interfacial region, and the flat surface. It was also estimated from the Hall measurements and photoluminescence spectroscopy that these single crystalline GZO films possessed good optical and electrical characteristics including the narrow band-width and higher intensity of exciton-related emission peak, Hall mobility as large as 66 cm2 V−1 s−1, and the resistivity as low as 1.69 × 10− 3 Ω cm.