Ultrasonic spray pyrolysis-induced growth of highly transparent and conductive F, Cl, Al, and Ga co-doped ZnO films

In this paper, the ultrasonic spray pyrolysis (USP) technology, under normal pressure conditions was adopts in this study to deposited ZnO films. The cheap zinc acetate, ammonium fluoride, and gallium chloride was used as Zn source, F source, Ga source and Cl source, respectively for deposited F, Cl, Al and Ga co-doped ZnO (FCAGZO) films. The influence of substrate temperature (Ts) on the morphology, structure, optical and electrical properties of ZnO thin films was studied. X-ray diffraction analysis shows that the Ts does not change the crystal structure of the ZnO film, and all films have a hexagonal wurtzite structure. With increase of Ts only the preferred orientation of the film changes from (1 0 0) to (0 0 2). X-ray photoelectron spectroscopy further confirmed the successful doping of ZnO by F, Cl, Al, and Ga, which accounts for the enhancement in carrier concentration in the FCAGZO films over that of pristine ZnO. As Ts increases, the resistivity first decreases, and then gradually increases. When the optimal substrate temperature Ts = 400 degrees C, the prepared FCAGZO film has a resistivity of 1.47 x 10(-3) Omega cm when rapid heat treatment in N-2 atmosphere at 750 degrees C, and the average transmittance exceeds 85% in the range of 400-1400 nm.