Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

Dewald, W.; Sittinger, V.; Szyszka, Bernd; Säuberlich, F.; Stannowski, Bernd; Köhl, D.; Ries, Patrick; Wuttig, Matthias

doi:10.1016/j.tsf.2013.02.027

Cited by 21 publications

(7 citation statements)

References 18 publications

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“…Stress formation and grain boundary relaxation model Figure 7(c) shows the (002) peak position to increase with the application of seed layers. Under the assumption of the biaxial-strain model, the peak shift can be explained either by a relaxation of compressive stress 20 or by an increase of tensile stress. Here, we attribute the peak shift to higher angles to rising tensile stress in the xy-plane.…”

Section: Discussionmentioning

confidence: 99%

“…[18][19][20][21] K€ ohl et al used ion beamed assisted sputtering to improve the c-axis orientation of ZnO deposited at room temperature. 18,19 The Xe þ ion bombardment induced highly oriented grains already in the nucleation stage of the growth process via an atomic peening mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…20 However, a simple dcprocess did not yield the desired results especially with regard to the etching morphology. Therefore, they applied a low rate, radio frequency (rf) sputtering process to deposit a thin seed layer knowing that the rf-process leads to films with suitable etching morphology.…”

Section: Introductionmentioning

confidence: 99%

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Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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This work elucidates the effect of the dopant aluminum on the growth of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films by means of a seed layer concept. Thin (<100 nm), highly doped seed layers and subsequently grown thick (∼800 nm), lowly doped bulk films were deposited using a ZnO:Al2O3 target with 2 wt. % and 1 wt. % Al2O3, respectively. We investigated the effect of bulk and seed layer deposition temperature as well as seed layer thickness on electrical, optical, and structural properties of ZnO:Al films. A reduction of deposition temperature by 100 °C was achieved without deteriorating conductivity, transparency, and etching morphology which renders these low-temperature films applicable as light-scattering front contact for thin-film silicon solar cells. Lowly doped bulk layers on highly doped seed layers showed smaller grains and lower surface roughness than their counterpart without seed layer. We attributed this observation to the beneficial role of the dopant aluminum that induces an enhanced surface diffusion length via a surfactant effect. The enhanced surface diffusion length promotes 2D-growth of the highly doped seed layer, which is then adopted by the subsequently grown and lowly doped bulk layer. Furthermore, we explained the seed layer induced increase of tensile stress on the basis of the grain boundary relaxation model. The model relates the grain size reduction to the tensile stress increase within the ZnO:Al films. Finally, temperature-dependent conductivity measurements, optical fits, and etching characteristics revealed that seed layers reduced grain boundary scattering. Thus, seed layers induced optimized grain boundary morphology with the result of a higher charge carrier mobility and more suitable etching characteristics. It is particularly compelling that we observed smaller grains to correlate with an enhanced charge carrier mobility. A seed layer thickness of 5 nm was sufficient to induce the beneficial effects.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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“…In this work, on the basis of many reports on controlling the crystallinity and/or surface morphology of AZO films in the early growth stages [11][12][13][14][15][16][17][18], we propose a resolution to the issue; a critical layer (CL) made from 10-nm-thick Ga-doped ZnO (GZO) films with a preferential c-axis orientation normal to the substrate as an interface layer between thicker AZO films by DC-MS and substrates. The CL comprises GZO films deposited by ion plating (IP) with dc arc discharge.…”

Section: Introductionmentioning

confidence: 99%

High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation

Nomoto¹,

Makino²,

Yamamoto³

2017

Nano Online

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Five hundred-nanometer-thick ZnO-based textured polycrystalline films consisting of 490-nm-thick Al-doped ZnO (AZO) films deposited on 10-nm-thick Ga-doped ZnO (GZO) films exhibited a high Hall mobility (μ H) of 50.1 cm 2 /Vs with a carrier concentration (N) of 2.55 × 10 20 cm −3. Firstly, the GZO films were prepared on glass substrates by ion plating with dc arc discharge, and the AZO films were then deposited on the GZO films by direct current magnetron sputtering (DC-MS). The GZO interface layers with a preferential c-axis orientation play a critical role in producing AZO films with texture development of a well-defined (0001) orientation, whereas 500-nm-thick AZO films deposited by only DC-MS showed a mixture of the c-plane and the other plane orientation, to exhibit a μ H of 38.7 cm 2 /Vs with an N of 2.22 × 10 20 cm −3 .

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“…In this sense, transparent conductive oxides (TCOs) are special materials that can simultaneously conduct electricity while having large band-gap. A band-gap energy larger than 3.0 eV and a carrier concentration of the order of 10 20 cm -3 or higher are required for high conductivity and visible light transmittance [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Such materials are called degenerate semiconductors.…”

Section: Introductionmentioning

confidence: 99%

Lanthanum-Doped Barium Stannate - a New Type of Critical Raw Materials-Free Transparent Conducting Oxide

Gogova

Suwardi

Kuznetsova

et al. 2017

Int. J. Adv. App. Phy. Res.

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A pulsed laser deposition-based process for growth of highly-doped epitaxial La:BaSnO3(001) layers on (001)oriented SrTiO3 is developed. The growth window of single-phase epitaxial Ba0.93La0.07SnO3 films is determined and the influence of growth parameters on crystalline quality is studied. Reciprocal space maps showed fully relaxed Ba0.93La0.07SnO3 epitaxial layers on SrTiO3 (001). The crystalline quality of material obtained was evidenced through HR-XRD measurements with a full width at half maximum (FWHM) of 290 arcsec for the Rocking curve of the symmetric (002) peak and 108 arcsec for the asymmetric (103) peak. The band gap of the layers, determined from Reflection measurements employing the Kubelka-Munk method, was estimated as 2.97-3.01 eV, i.e. very suitable for the applications envisaged. The layers demonstrated electrical conductivity value of 1024 (Ω•cm)-1 at a free carrier concentration of 2.18×10 21 cm-3 and a high transparency (up to 90%) in the visible and NIR range of spectrum. The Ba0.93La0.07SnO3 layers grown could be regarded as a cost-effective and thermally and chemically stable alternative to highly doped ZnO-based transparent conductive oxides and to In2O3:Sn in applications ranging from solar energy utilization to optoelectronics as well as for the emerging field of transparent and radiation hard electronics.

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Advanced properties of Al-doped ZnO films with a seed layer approach for industrial thin film photovoltaic application

Cited by 21 publications

References 18 publications

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

High-Hall-Mobility Al-Doped ZnO Films Having Textured Polycrystalline Structure with a Well-Defined (0001) Orientation

Lanthanum-Doped Barium Stannate - a New Type of Critical Raw Materials-Free Transparent Conducting Oxide

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