Characteristics of Al-doped ZnO films grown by atomic layer deposition for silicon nanowire photovoltaic device

We report the structural, electrical, and optical characteristics of Al-doped ZnO (ZnO:Al) ?lms deposited on glass by atomic layer deposition (ALD) with various Al_2O3?lm contents for use as transparent electrodes. Unlike ?lms fabricated by a sputtering method, the diffraction peak position of the ?lms deposited by ALD progressively moved to a higher angle with increasing Al₂O₃?lm content. This indicates that Zn sites were effectively replaced by Al, due to layer-by-layer growth mechanism of ALD process which is based on alternate self-limiting surface chemical reactions. By adjusting the Al₂O₃?lm content, a ZnO:Al ?lm with low electrical resistivity (9.84 × 10^-4ω cm) was obtained at an Al₂O₃?lm content of 3.17%, where the Al concentration, carrier mobility, optical transmittance, and bandgap energy were 2.8 wt%, 11.20 cm²V^-1s^-1, 94.23%, and 3.6 eV, respectively. Moreover, the estimated ?gure of merit value of our best sample was 8.2 mω^-1. These results suggest that ZnO:Al ?lms deposited by ALD could be useful for electronic devices in which especially require 3-dimensional conformal deposition of the transparent electrode and surface passivation