Paper TF-TuM1
Aluminum-Doped Zinc Oxide via Spatial ALD: Process Impact on Film Morphology, Electrical Conductivity and Stability

Tuesday, October 31, 2017, 8:00 am, Room 20

Aluminum-doped zinc oxide (AZO) is an attractive transparent conductive material because of to its nontoxic, earth-abundant material composition. A wide range of electrical properties have been reported for AZO deposited using a variety of techniques and a range of process conditions. This talk will focus on the AZO grown using spatial atomic layer deposition (SALD), and the impact of process conditions on the electrical, optical and crystallographic properties of the resultant AZO films. We will report primarily on those AZO films deposited using a co-flow of dimethyl aluminum isopropoxide (DMAI) and diethyl zinc (DEZ) as the metal precursors, and water as the oxygen source.

We will share our current understanding of the mechanisms responsible for the interplay between process parameters and material properties, including the correlation of film properties such as doping-level and crystallographic structure to the end-use properties of conductivity and optical transparency. For reference, we have deposited AZO having a bulk resistivity of 2.7 × 10^-4 Ω-cm and an average visible transmission of 85%, obtained from 204 nm thick AZO films deposited at 300°C. This compares well to commercially available ITO coatings having, for example, about 1.2 × 10^-4 Ω-cm and 82% average visible transmission for film thicknesses between 150 nm and 200 nm.

In addition, the impact of passivating the AZO surface with very thin aluminum oxide (Al₂O₃) will also be reported. We have found that passivation with Al₂O₃ enhances conductivity through an increase in both mobility and carrier concentration. Improved thermal stability during elevated annealing conditions in air was also observed for alumina-passivated AZO samples