Temperature-dependent electrical characterization of nitrogen-doped ZnO thin film: vacuum annealing effect

Temperature-dependent Hall effect measurements were carried out at an N-doped ZnO thin film grown by the reactive sputtering method onto (001) Si substrate before and after being vacuum annealed at 900 degrees C. p-Type ZnO thin film was obtained with a relatively high mobility of similar to 60 cm(2) V(-1) s(-1), a high carrier concentration of 2.5 x 10(17) cm(-3) and a low resistivity of 0.4 Omega cm. After vacuum annealing, the temperature dependence of electrical parameters such as mobility and carrier concentration showed highly different characteristics. Time-resolved photoluminescence (TRPL), PL and x-ray diffraction measurements (XRD) were performed after the annealing process to check whether the high-temperature annealing can remove the ZnO film on Si or not. The PL measurement shows band-to-band recombination at 360 nm and TRPL shows the exciton recombination lifetime to be 571.7 ps. The XRD measurement reveals highly preferred c-axis (0002) orientation. Activation energies were calculated using the ln sigma versus 1000 T(-1) plot to be 20 meV for the as-grown and 24 and 6.8 meV after the vacuum annealing process.