ZnO films prepared by two-step MOCVD process for use as front TCO in silicon-based thin film solar cells

In this paper, we report on ZnO films prepared by MOCVD technique with two-step deposition process. Effects of the thickness of the second layer were systematically investigated. It was found that with an increase in the thickness of the second layer, the surface morphology of multi-layer ZnO films show a mixture of both small spheres and a pyramid-like texture appeared on the surface. Furthermore, transmittance of the films increased remarkably. We also found that the electrical properties of the films slightly changed because overall electrical properties are mainly controlled by the first layer. Using multi-layer ZnO films with a thick second layer, we improved the transparency in the whole optical region of these films while preserving their good electrical properties.