The effect of aluminum sources of nitrate, chloride, and sulphate salts as dopant chemicals on the characteristics of aluminum-doped zinc oxide particles prepared via ultrasonic spray pyrolysis have been investigated. The structural, optical, morphological and electrical characteristics were examined using an X-ray diffraction (XRD) technique, UV-vis spectrophotometer, scanning electron microscopy (SEM) and a four-point probe method, respectively. Using the three aluminum sources as dopants with a molar ratio [Al]/[Zn] as high as 8% did not change the hexagonal wurtzite crystal structure of ZnO. The use of a nitrate source indicated that the crystal size was decreased less than that of chloride and sulphate sources when the dopant concentration was increased. In general, increasing the dopant concentration led to a decrease in the transmittance percentages. Al-doped ZnO particles had a more spherical and smoother surface than those of undoped ZnO particles. The film resistance values of [Al]/[Zn]= 2% were 1.89, 2.31 and 4.31 10-2. cm for aluminum sources of sulphate, chloride and nitrate, respectively.