Microstructure evolution of Al-doped zinc oxide and Sn-doped indium oxide deposited by radio-frequency magnetron sputtering: A comparison

Nie, Man; Bikowski, André; Ellmer, K.

doi:10.1063/1.4916725

Cited by 13 publications

(16 citation statements)

References 29 publications

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“…As mentioned in the previous section, thickness dependence of electrical properties is one of the main limitations of using AZO films. The high resistivity of very thin films was investigated by several authors . It is often related to the existence of the thin interfacial layer, which does not contribute to the film conductivity.…”

Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

“…Look et al proposed a mobility model described by the equation:

μ true(boldd true) = \frac{μ_{\infty}}{1 + \frac{{bold-italicd}^{*}}{d - δ d}}

where d is the thickness,

δ d

is the thickness of the depleted layer and d * is a function of n ,

μ true(\infty true)

. Nie et al fitted the dependence of the resistivity ρ ( d ) on the thickness d using the Fuchs‐Sondheimer model (F‐S model) according to the Equation:

ρ true(d true) = ρ_{\infty} true(1 + \frac{3 l_{e} true(1 - p true)}{8 true(d - d_{0} true)} true)

where

ρ_{\infty}

the bulk resistivity, l e is the mean free electron path, and p is the diffuse reflection coefficient at the surface and interface, respectively. Both models assume a non‐conductive layer with thickens

δ d

or d 0 , bulk mobility

μ_{\infty}

and volume resistivity

ρ_{\infty}

.…”

Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

“…The AZO film can be described as a stack of very thin layers with different conductivity and thus the resulting sheet conductance is the sum of the conductivities. The values of σ S as a function of the film thickness taken from are displayed in Figure a. The evolution of sheet conductance was fitted according to empirical equation

σ_{s} = h σ_{b u l k} exp {(- \frac{h_{0}}{h})}^{}^{}

where coefficient σ bulk is the slope of the linear part, which expresses bulk conductivity and h 0 is the intersection the asymptote and x‐axis which expresses the non‐conductive layer close to the substrate.…”

Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

“…If ρ is uniform throughout the film, these two quantities are simply related as ρ = R s h , that is, R s decreases with increasing film thickness. However, this assumption is not fully ensured for AZO (in contrast to ITO) films due to the significantly lower conductivity of the film close to the interface between the film and the substrate …”

Section: Introductionmentioning

confidence: 99%

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Possibilities of Increasing the Usability of Sputtered AZO Films as a Transparent Electrode

Novák

2019

Physica Status Solidi (a)

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Aluminum-doped zinc oxide (AZO) is a suitable material for use as transparent electrode. Due to its lower price it is applied in the production of silicon solar cells. However, it is difficult to obtain suitable electrical properties at low deposition temperatures. Moreover, the AZO films with low thickness exhibit significantly higher average resistivity, which limits their usability, especially if they are prepared on flexible substrates. A lot of effort is invested to replace indium tin oxide (ITO) to a much greater extent now, since Indium is rare and its price is rising, thus the preparation of lowthickness AZO films at low temperature is also subject of intense research. The presented paper summarizes the reported results, discusses the causes of the differences between ITO and AZO films, and suggests the direction of research and the potential solution that should lead to increased usability of AZO films and also possible replacement of ITO films.

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Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

“…Look et al proposed a mobility model described by the equation:

μ true(boldd true) = \frac{μ_{\infty}}{1 + \frac{{bold-italicd}^{*}}{d - δ d}}

where d is the thickness,

δ d

is the thickness of the depleted layer and d * is a function of n ,

μ true(\infty true)

. Nie et al fitted the dependence of the resistivity ρ ( d ) on the thickness d using the Fuchs‐Sondheimer model (F‐S model) according to the Equation:

ρ true(d true) = ρ_{\infty} true(1 + \frac{3 l_{e} true(1 - p true)}{8 true(d - d_{0} true)} true)

where

ρ_{\infty}

δ d

or d 0 , bulk mobility

μ_{\infty}

and volume resistivity

ρ_{\infty}

.…”

Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

σ_{s} = h σ_{b u l k} exp {(- \frac{h_{0}}{h})}^{}^{}

Section: The Thickness Dependence Of Electrical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Possibilities of Increasing the Usability of Sputtered AZO Films as a Transparent Electrode

Novák

2019

Physica Status Solidi (a)

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“…The AZO is considered to be a cheap and non‐toxic candidate to replace the most used indium thin oxide, as high transparency and the lowest resistivity in the range of 2–4 × 10 −4 Ω · cm can be achieved . However, it is still difficult to obtain such good electrical properties on thermally sensitive substrates, as the optimal deposition temperature is about 300 °C . The preparation of AZO films at temperatures up to 100 °C is very important for applications in the field of flexible electronics.…”

Section: Introductionmentioning

confidence: 99%

Influence of Oxygen on the Resistivity of Co‐Sputtered Transparent AZO Films

Novák

Kozák²,

Šutta

et al. 2018

Physica Status Solidi (a)

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In the present work co-sputtering from ceramic and metallic targets is used to reduce the oxygen content in aluminium doped zinc oxide. Films with thickness between 200 and 220 nm are sputtered at 100 and 250 C and investigated by X-ray diffraction, energy dispersive spectroscopy, and Hall measurements. It is found that reducing of the incorporated oxygen in the film leads to higher carrier concentration, mainly due to better effective activation of Al donors. Higher temperatures result in better carrier mobility due to improving the crystallinity. The best resistivity of 1.4 Â 10 À3 Ω cm of the highly transparent film prepared at 100 C is achieved. A larger oxygen reduction leads to lower resistivity, but also results in the significant deterioration of transmittances.

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Correlation between Hall Mobility and Optical Mobility in Aluminum‐Doped ZnO Films via Boundary Scatterings and Estimation of Donor Compensation Ratio

Ghosh

Basak

2019

Physica Status Solidi (b)

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A correlation between the Hall and optical mobility via boundary (BND) scatterings arising from grain as well as surface boundaries in radio frequency (RF) sputtered Al-doped ZnO (AZO) films done by a comprehensive study on the electrical carrier transport and near infrared optical transmittance properties. AZO films with thicknesses from 100 to 1550 nm are grown by sputtering 1.9 wt% Al 2 O 3 -doped ceramic target under identical growth conditions. The Hall measurement shows an increase in the carrier concentration value from 6.93 Â 10 20 to 1.1 Â 10 21 cm À3 with a mobility value (μ Hall ) in the range of 4.98-10.3 cm 2 (V s) À1 as the thickness increases. Unprecedentedly, it is shown that the optical mobility value (μ opt ) calculated using Drude theory is higher than that of the μ Hall up to a film thickness of %1000 nm beyond which both the values merges. Though the carrier concentration is higher than 5 Â 10 20 cm À3 , BND scattering playing an important role in addition to the in-grain scattering below a thickness of %1000 nm is demonstrated. Considering the BND scattering, donor compensation ratio is calculated and is uniquely found to vary with the film thickness.

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Microstructure evolution of Al-doped zinc oxide and Sn-doped indium oxide deposited by radio-frequency magnetron sputtering: A comparison

Cited by 13 publications

References 29 publications

Possibilities of Increasing the Usability of Sputtered AZO Films as a Transparent Electrode

Possibilities of Increasing the Usability of Sputtered AZO Films as a Transparent Electrode

Influence of Oxygen on the Resistivity of Co‐Sputtered Transparent AZO Films

Correlation between Hall Mobility and Optical Mobility in Aluminum‐Doped ZnO Films via Boundary Scatterings and Estimation of Donor Compensation Ratio

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