Influence of growth temperature on dielectric strength of Al 2 O 3 thin films prepared via atomic layer deposition at low temperature

Thin films grown via atomic layer deposition (ALD) suffer from insufficient growth rate and unreliability for temperature-sensitive electronic substrates. This study aimed to examine the growth characteristics and dielectric strength of ALD Al 2 O 3 films grown at low temperatures (≤ 150 °C) for potential application in flexible electronic devices. The growth rate of the Al 2 O 3 films increased from 0.9 to 1.1 Å/cycle with increasing temperature and saturated at growth temperatures ≥ 150 °C, which is the critical temperature at which a complete oxidation reaction occurred. The dielectric strength was also improved with increasing growth temperature, and the films grown at 150 °C showed a high breakdown field strength (~ 8.3 MV/cm), attributable to the decrease in the carbon impurities and oxygen defects, as confirmed by X-ray photoelectron spectroscopy. Even at low growth temperatures (≤ 150 °C), ALD Al 2 O 3 films showed an overall amorphous structure and extremely smooth surfaces regardless of the growth temperature.