Abstract:The conductivity and optical transmission of ITO thin films, produced from nanoparticle suspensions, are improved by microwave post annealing.
“…Films deposited for only 90 seconds were found to be conducting, with the lowest sheet resistance value of 497 Ω/□ and a transparency of 70% at 400 nm, giving a resistivity of 1.99 × 10 −2 Ω.cm. Other materials with similar resistivity include ITO fabricated by different methods 70,71 . Our brief experiment, without optimization, suggested that conducting InN thin films could be fabricated using AACVD.Figure 5( A ) Carrier concentration determined by Mott Schottky Analysis for various composite nitride thin films; ( B ) Band edges of InN, GaN and composite thin films relative to the RHE reference scale as measured by Mott-Schottky.…”
III-nitride materials have been linked with a vast number of exciting applications from power electronics to solar cells. Herein, polycrystalline InN, GaN and systematically controlled InxGa1−xN composite thin films are fabricated on FTO glass by a facile, low-cost and scalable aerosol assisted chemical vapor deposition technique. Variation of the indium content in the composite films leads to a dramatic shift in the optical absorbance properties, which correlates with the band edges shifting between those of GaN to InN. Moreover, the photoelectrochemical properties are shown to vary with indium content, with the 50% indium composite having an external quantum efficiency of around 8%. Whilst the overall photocurrent is found to be low, the photocurrent stability is shown to be excellent, with little degradation seen over 1 hour. These findings demonstrate a new and low-cost method for fabricating polycrystalline III-nitrides, which have a range of interesting properties that are highly sought after for many applications.
“…Films deposited for only 90 seconds were found to be conducting, with the lowest sheet resistance value of 497 Ω/□ and a transparency of 70% at 400 nm, giving a resistivity of 1.99 × 10 −2 Ω.cm. Other materials with similar resistivity include ITO fabricated by different methods 70,71 . Our brief experiment, without optimization, suggested that conducting InN thin films could be fabricated using AACVD.Figure 5( A ) Carrier concentration determined by Mott Schottky Analysis for various composite nitride thin films; ( B ) Band edges of InN, GaN and composite thin films relative to the RHE reference scale as measured by Mott-Schottky.…”
III-nitride materials have been linked with a vast number of exciting applications from power electronics to solar cells. Herein, polycrystalline InN, GaN and systematically controlled InxGa1−xN composite thin films are fabricated on FTO glass by a facile, low-cost and scalable aerosol assisted chemical vapor deposition technique. Variation of the indium content in the composite films leads to a dramatic shift in the optical absorbance properties, which correlates with the band edges shifting between those of GaN to InN. Moreover, the photoelectrochemical properties are shown to vary with indium content, with the 50% indium composite having an external quantum efficiency of around 8%. Whilst the overall photocurrent is found to be low, the photocurrent stability is shown to be excellent, with little degradation seen over 1 hour. These findings demonstrate a new and low-cost method for fabricating polycrystalline III-nitrides, which have a range of interesting properties that are highly sought after for many applications.
“…The microwave-assisted annealing was carried out using a microwave oven (Microwave research Applications Inc. BP-211/50, USA) operating at 2.45 GHz frequency with a maximum power of 3000 W. The microwave heat treatment was facilitated by using SiC susceptor tiles, placed on both sides of the doped ZnO pellets. The heat loss was minimized by shielding the sample within thermally insulating blocks. , The pellets, SiC tiles, and insulating blocks were placed inside a custom-made quartz vessel fitted with a gas inlet and outlet and a zirconium oxide window to allow monitoring of the temperature using an IR thermometer. Prior to the microwave annealing, the quartz vessel containing the TCO pellet was purged with the 5% H 2 /N 2 gas mixture at 1825 mL min –1 (BOC, UK) for 5 min.…”
Section: Experimental Methodsmentioning
confidence: 99%
“…Aerosol-assisted chemical transport (AACT) was used to fabricate thin films from nanoparticle suspensions. This method has been recently developed in our laboratory and has been used to deposit transparent conducting ITO thin films . For the deposition, an AGZO nanoparticle suspension was prepared by dispersing 0.2 g of washed powder (ca.…”
Section: Experimental Methodsmentioning
confidence: 99%
“…In order to obtain a better dispersion, 0.05 mL of formic acid was added to the nanoparticle suspension . Moreover, ethyl cellulose (0.01 g) (Sigma-Aldrich) was added as a binding agent . The suspension was then sonicated for 5 min using a sonicator probe (S-4000, Misonix, Inc., USA).…”
Section: Experimental Methodsmentioning
confidence: 99%
“…The heat loss was minimized by shielding the sample within thermally insulating blocks. 26,27 The pellets, SiC tiles, and insulating blocks were placed inside a custom-made quartz vessel fitted with a gas inlet and outlet and a zirconium oxide window to allow monitoring of the temperature using an IR thermometer. Prior to the microwave annealing, the quartz vessel containing the TCO pellet was purged with the 5% H 2 /N 2 gas mixture at 1825 mL min −1 (BOC, UK) for 5 min.…”
This
work reports the microwave-assisted fabrication of highly
conducting Al-doped ZnO (AZO), Ga-doped ZnO (GZO), and Al, Ga codoped
ZnO (AGZO) materials as cheaper earth abundant alternatives to indium
tin oxide (ITO) for transparent conducting applications. All three
doped ZnO powder samples were compressed into pellets, and their electrical
properties were evaluated after the postsynthesis heat treatment.
The heat treatment was performed by sintering the pellets at 600 °C
in a reducing atmosphere using either conventional radiant annealing
for 3 h or microwave annealing for 90 s. The Al and Ga dopant levels
were systematically varied from 0.5 to 2.5 at. %, and it was found
that the lowest resistivity values for the pelleted singly doped ZnO
powders exist when the doping level is adjusted to 1.5 at. % for both
AZO and GZO, giving resistivity values of 4.4 × 10–3 and 4.3 × 10–3 Ω·cm, respectively.
The lowest resistivity of 5.6 × 10–4 Ω·cm
was achieved for the pelleted codoped AGZO powder using the optimized
Al and Ga dopant levels. Notably, this value is one magnitude lower
than the best literature reported value for conventionally synthesized
codoped AGZO powder. The resistivity
values obtained for the pellets after radiant and microwave postsynthesis
heat treatment are comparable, although the microwave heat treatment
was performed only for 90 s, compared to 3 h for conventional radiant
heat treatment. Hence, significant gains were made in the postannealing
step by reducing time, cost, and energy required, benefiting our thrust
for finding sustainable routes toward alternative low-cost transparent
conducting oxides. As a proof of concept, transparent conducting thin
films were fabricated via a simple aerosol-assisted deposition technique
using our best conducting AGZO nanoparticles. The films exhibited
a visible transmittance as good as 90% and a resistivity of 5.7 ×
10–3 Ω·cm, which can compete with the
existing high cost ITO films.
Aqueous dispersions of tin-doped indium oxide (ITO) nanopowder were prepared and the effect of the addition of PEG 400, Tween 80 and β-alanine as dispersants was investigated using zeta potential and particle size distribution measurements. Both PEG 400 and β-alanine were found to produce stable dispersions that were used to deposit ITO thin films on glass substrates by dip and spin coating methods. The ITO thin films were heat-treated using both conventional and microwave heat treatment in order to improve the inter-particle connections and hence the resistivity and transparency of the films. All the films exhibited an average transmittance of >80% over the visible spectrum after being subjected to the heat treatment process. ITO films prepared with no dispersant showed very high resistivity values for both heating methods, however addition of 2 wt% PEG 400 to the dispersion yielded a reduction in the resistivity values to 1.4 × 10 -1 Ω cm and 3.8 × 10 -2 Ω cm for conventionally and microwave treated films, respectively. The surface morphological studies confirmed that addition of dispersants improved the film uniformity and inter-particle connections of the ITO films considerably.
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