Texture-etched AZO Substrates As Front Contacts In Solar Cells

AZO thin films were grown by DC magnetron sputtering and characterized for its applications in Si-based thin film solar cells as the front electrode. The main work includes the following two aspects.AZO thin films were grown on glass substrates using the Zn-Al alloy target with 4at.%Al content. The influence of substrate temperature, O2 pressure, and sputtering power on the electrical, optical properties and morphology of films was studied. Then the optimal parameters were determined by the experiments and analysis, which included the basis pressure of 5.0x1 O-Pa, working pressure of 0.5Pa, substrate temperature of 400℃, sputtering power of 150W, and Ar:O2 ratio of 100:6. The film thickness was 865nm when the sputtering time was 1 Omin. The resistivity of the film was 8.35X10-4Ωcm. with hall mobility and carrier concentration of 20.7cm2/V.s and 3.59×102Ocm-3 respectively. The visible light transparence was above 90%. The high visible light transmittance and low resistivity of the film was the basis of its applications in devices.The textured AZO thin films were prepared by wet chemical etching. The influence of substrate temperature, sputtering pressure, working pressure, Ar:O2, etching solution species, and etching time on the surface morphologies of films was studied. The results showed that the properties of the textured AZO films were improved as the increasing of the substrate temperature and the decreasing of the working pressure. The optimal parameters for preparing textured AZO films were decided by experiments and analysis:they were substrate temperature of 400℃. sputtering pressure of 0.5Pa,0.5%dilute hydrochloric acid as the etching solution, and etching time of 15s.