Transparent and conductive ZnO:Al films deposited by large area reactive magnetron sputtering

Abstract

A new coating technology has been developed for large area deposition of transparent and conductive ZnO:Al films. Reactive AC magnetron sputtering from metallic Zn:Al has been performed at low substrate temperature below 200 °C using the new CleanMag technology of applied films based on moving magnets for layers with low defect density and with conventional reactive AC magnetron sputtering using static magnets (Applied Films TwinMag). Process stabilization at non-stable process conditions in transition mode has been achieved using closed loop control of discharge power according to fast oxygen partial pressure measurements taken by a lambda probe. Films with film thickness of 800–1000 nm deposited with dynamic deposition rate of a D>60 nm m/min exhibit low resistivity of ρ<270 μΩ cm and small absorption ( k<2×10 −3) in the visible range. The homogeneity of sheet resistance on float glass substrates with dimension of 600×1000 mm 2 is better than ±6%. Film properties such as etching characteristics and haze can be controlled due to adjustment of total pressure and substrate temperature for large are a-Si:H thin film photovoltaic applications [1].