Synthesis of AlOx thin films by atmospheric-pressure mist chemical vapor deposition for surface passivation and electrical insulator layers

Abstract

Aluminum oxide (AlOx) thin films were grown using aluminum acetylacetonate [Al(acac)3] as a source material with methanol and water as the solvent by mist chemical vapor deposition, while also exposing some films to water or methanol mists after fabrication. The incorporation of –OH groups into the AlOx network that is fabricated from Al(acac)3 and using solely methanol as a solvent generates both malformed Al(OH) network and nonuniformity. However, the addition of a small amount of water in the solvent during film growth decreases the deposition rate due to the hydrogen bond in water molecules but markedly removes –OH groups from the growth surface of the AlOx network and improves the surface uniformity. The AlOx thin films grown with a methanol:water ratio of 7:3 at 400 °C exhibit a recombination velocity of 16 cm/s, a breakdown field of 6.9 MV/cm, and an interface trap density of 4.2 × 1010 cm−2 eV−1, which are compatible with the AlOx grown by the other vacuum-based methods.

AlOx Thin Films Synthesized by Mist Chemical Vapor Deposition, Monitored by a Fast-Scanning Mobility Particle Analyzer, and Applied as a Gate Insulating Layer in the Field-Effect Transistors

“…When T f was increased from 400 to 600 °C, the n -values increased from 1.62 to 1.66–1.67 at 3.5 eV, whereas RMS values for the 20 × 20 μm 2 area of the films decreased from 6.45 to 1.30 nm. These results suggest that the diffusivity of the deposition precursor is enhanced at the growth surface and promotes the removal of residual Al­(OH) bonds , …”

“…Additionally, mist-CVD can be employed to prepare metal-oxide–alloy thin films using metal acetylacetonates such as aluminum acetylacetonate (Al­(acac) 3 ), which are cost-effective, chemically stable, and low-vapor-pressure materials. In mist-CVD, the film is grown via thermal decomposition of the source material, which is dissolved in a solvent such as water or low-molecular-weight alcohol. , Thus far, most of the studies on the film deposition by mist-CVD provide a correlation between the film property and its device performance. However, studies on the growth mechanism and role of the solvent in the synthesis of AlO x thin films are limited. , Herein, we studied the fabrication of AlO x thin films through mist-CVD from Al­(acac) 3 /methanol/water (Al­(acac) 3 /MeOH/H 2 O) solutions at different MeOH/water ratios as well as postfabrication exposure to water and MeOH mist .…”

“…In mist-CVD, the film is grown via thermal decomposition of the source material, which is dissolved in a solvent such as water or low-molecular-weight alcohol. , Thus far, most of the studies on the film deposition by mist-CVD provide a correlation between the film property and its device performance. However, studies on the growth mechanism and role of the solvent in the synthesis of AlO x thin films are limited. , Herein, we studied the fabrication of AlO x thin films through mist-CVD from Al­(acac) 3 /methanol/water (Al­(acac) 3 /MeOH/H 2 O) solutions at different MeOH/water ratios as well as postfabrication exposure to water and MeOH mist . We found that additional H 2 O was consumed to preferentially remove Al­(OH) bonds (caused by MeOH) on the growth surface.…”

“…In mist-CVD, the film is grown via thermal decomposition of the source material, which is dissolved in a solvent such as water or low-molecular-weight alcohol. 27,28 Thus far, most of the studies on the film deposition by mist-CVD provide a correlation between the film property and its device performance. However, studies on the growth mechanism and role of the solvent in the synthesis of AlO x thin films are limited.…”

“…However, studies on the growth mechanism and role of the solvent in the synthesis of AlO x thin films are limited. 28,29 Herein, we studied the fabrication of AlO x thin films through mist-CVD from Al(acac) 3 /methanol/ water (Al(acac) 3 /MeOH/H 2 O) solutions at different MeOH/ water ratios as well as postfabrication exposure to water and MeOH mist. 28 We found that additional H index and uniformity were obtained by adjusting the MeOH/ H 2 O mixture ratio to 7:3, and a T f of 400 °C.…”