Study on the Adhesion Force Between Ga-Doped ZnO Thin Films and Polymer Substrates

Flexible Ga doped ZnO (GZO) transparent conductive thin films were prepared on polycarbonate (PC) substrates at room temperature by magnetron sputtering. The adhesive property between the GZO film and the PC substrate was investigated quantitatively by the scratch test, which is designed for the quantitative assessment of the mechanical integrity of coated surfaces. The effect of the sputtering pressures on the adhesion forces for the GZO films was investigated. When the sputtering pressure varied from 0.2 to 0.5 Pa, no obvious adhesion force alteration was observed. However, when the sputtering pressure was increased to 0.7 Pa, the adhesion force was decreased. The lowest square resistance of the GZO film was 18.6 Ω/sq. Regardless of the sputtering pressure, the transmittance in the visible light was about 90%. When the sputtering pressure was 0.4 Pa, the optimal figure of merit (Φ_TC) was 2.5×10^-2 Ω^-1, indicating that the optimal pressure was 0.4 Pa.