Nanocrystalline zinc oxide for surface morphology control in thin-film silicon solar cells

Zinc oxide (ZnO) is a widely used transparent conductive material for thin-film solar cells. Naturally textured ZnO deposited by low pressure chemical vapor deposition (LPCVD) is currently used to prepare high efficiency thin film silicon solar cells. However it is known that a strong roughness can disturb the growth of microcrystalline silicon and induce performance losses. An alternative approach denominated “nanocrystalline ZnO” is presented which allows to control surface roughness and haze during growth independently of other layer properties such as thickness, doping or conductivity for layers thicker than approximately 80nm. Surface morphologies, optical properties and material properties of the nanocrystalline ZnO layers together with solar cells results are presented. •Preferential orientation of LPCVD ZnO can be suppressed by an in-situ treatment.•Haze control independently of the thickness for layers thicker than 80nm.•Haze control independently of the sheet resistance.•Controlled smoothening of the LPCVD ZnO surface morphology.•Improvement of µc-Si:H material quality on smoothened ZnO.