Influence of growth temperature on dielectric strength of Al2O3 thin films prepared via atomic layer deposition at low temperature

Abstract

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 Al2O3 films grown at low temperatures (≤ 150 °C) for potential application in flexible electronic devices. The growth rate of the Al2O3 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 Al2O3 films showed an overall amorphous structure and extremely smooth surfaces regardless of the growth temperature.

Process temperature-dependent interface quality and Maxwell–Wagner interfacial polarization in atomic layer deposited Al2O3/TiO2 nanolaminates for energy storage applications

“…S2† demonstrates the high-resolution scans and the detailed deconvoluted spectra of Al 2p and O 1s core levels in Al 2 O 3 thin films, where the contribution of H-related intrinsic impurity/surface contamination (such as –OH or CH 4 ) is found to decrease with the increase in T d from 200 to 300 °C. This decrement in the defect/impurity concentration in Al 2 O 3 with the increase in T d is in line with literature reports, 29,66 and it actually contributes to improving the insulating nature of Al 2 O 3 sublayers in ATA NLs. Fig.…”

“…5a displays a slight decrease in low frequency tan δ values with an increase in T d from 150 to 300 °C, which suggests a small improvement in the insulating properties of the Al 2 O 3 barrier layers in these NLs plausibly owing to the reduction in impurity concentration with the increase in T d . 29 Additionally, the high-frequency shift of the M–W relaxation peak positions (depicted with arrows) clearly indicates an increase in the conductivity of TiO 2 sublayers with an increase in T d from 150 to 300 °C, plausibly owing to an increase in the concentration of oxygen vacancy (OV) related defect carriers in TiO 2 sublayers. 6,28…”

“…For all the ATA NLs, R A ≫ R T and the monotonous increment in the total resistance ( R = R T + R A ) of the NLs with the increase in T d clearly support the improvement in the insulating nature of the Al 2 O 3 sublayers as concluded from the frequency dependent σ AC and tan δ measurements and are plausibly owing to the significant decrement in impurity concentration. 29,42,64,65…”

“…25–27 Additionally, the ALD deposition temperature has a strong influence on the concentration of oxygen vacancies (OVs) in oxide thin films, the impurity level, structural defects, carrier concentration, and its mobility, which directly affect the conductivity and hence the electrical and dielectric properties of ALD grown thin films. 28,29 Since the higher conductivity contrast between Al 2 O 3 /TiO 2 sublayers and better interface quality are the primary requirements for exhibiting M–W interfacial polarization driven enhanced dielectric properties in such NLs, 6 the effect of substrate temperature on the device performance of ATA NLs needs to be investigated thoroughly.…”

Fabrication of Aluminum Oxide Thin-Film Devices Based on Atomic Layer Deposition and Pulsed Discrete Feed Method

“…Aluminum oxide thin film has been used as the gate dielectric for transparent thin film transistors [ 1 , 2 ], the packaging of photovoltaic devices [ 3 ], the diffusion barrier layer of gas [ 4 ] and the surface coating of electrodes and photoelectrodes [ 5 ]. Al 2 O 3 thin films can be prepared by different coating techniques, such as high power impulse magnetron sputtering (HiPIMS) [ 6 ], pulsed laser deposition (PLD) [ 7 ], electron beam evaporation [ 8 , 9 , 10 ], sol-gel [ 11 ] and atomic layer deposition (ALD) [ 12 , 13 , 14 , 15 ]. Among these techniques, atomic layer deposition (ALD) is a key process in the optoelectronic semiconductor industry.…”