Drastic Change in Electrical Properties of Electrodeposited ZnO: Systematic Study by Hall Effect Measurements

We report a systematic study of the electrical properties of ZnO films prepared by galvanostatic electrodeposition from an aqueous zinc nitrate solution. The structural characterization of the ZnO films electrodeposited at various applied current densities and deposition temperatures are carried out with XRD and FESEM, and the electrical properties including resistivity, carrier density, and carrier mobility are determined by Hall effect measurements at room temperature. The Hall effect measurements reveal that the resistivity changes drastically by about 5 and 6 orders of magnitude with the applied current density (0.1-2.0 mA cm(-2)) and the deposition temperature (60-80 degrees C), respectively. The variation in the resistivity is mainly attributed to carrier density not mobility and shows a good correlation with the degree of c-axis orientation of the ZnO films. Annealing effect on the electrical properties of the ZnO films is also examined similarly, revealing that the resistivity increases by similar to 50 times with increasing temperature (150-500 degrees C) accompanied by the formation of nanosized holes.