Influence of damp heat on the optical and electrical properties of Al-doped zinc oxide

Greiner, D.; Papathanasiou, N.; Pflug, Andreas; Ruske, F.; Klenk, R.

doi:10.1016/j.tsf.2008.10.107

Cited by 39 publications

(28 citation statements)

References 10 publications

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“…Note furthermore that we evaluated the damping frequency C Dr at the plasma frequency X Dr to obtain q opt , whereas several authors determined l opt or q opt by using the lowfrequency damping constant C L . [37][38][39][40][41] Our evaluation is in line with the original publication of Mergel et al 29 and we will see that the obtained resistivity values are reasonable within the general understanding of conductivity in the investigated material.…”

Section: Methodssupporting

confidence: 89%

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: Methodssupporting

confidence: 89%

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 any case, the experiment has shown that the n-ZnO in the P2 scribe, being important for the conducting connection between the single module cells, is altered during the aging, thus identifying one source of deterioration. These findings are in accordance with measured conductivity changes in n-ZnO films after DH-tests [84]. However note that properly encapsulated CIGSSe modules pass even extended DHtests without significant deterioration.…”

Section: Spatially-resolved Xes Investigation Of the Interconnection supporting

confidence: 90%

Synchrotron-based spectroscopy for the characterization of surfaces and interfaces in chalcopyrite thin-film solar cells

Lauermann

Bär

Fischer

2011

Solar Energy Materials and Solar Cells

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“…A similar damp heat degradation behavior has been observed also for sputtered and CVD ZnO films by several authors. 4,[21][22][23][24][25][26] They propose that the diffusion of environmental gasses (e.g., oxygen, carbon dioxide, and water vapor) along the grain boundaries of ZnO films leads to a local increase in the density of traps states for the free carriers and in a higher potential barrier, which hinders the mobility of the carriers among the grains. 14 The carriers flow across the grain boundaries via thermionic emission and tunneling increases with the Fermi level, and therefore, films with higher carrier density are typically found to have more stable electrical properties in a harsh environment, as also shown in Figs.…”

Section: Resultsmentioning

confidence: 99%

On the environmental stability of ZnO thin films by spatial atomic layer deposition

Illiberi¹,

Scherpenborg²,

Theelen³

et al. 2013

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Undoped and indium-doped ZnO films have been deposited by atmospheric spatial atomic-layer-deposition (spatial-ALD). The stability of their electrical, optical, and structural properties has been investigated by a damp-heat test in an environment with 85% relative humidity at 85 °C. The resistivity of the ZnO films increased during damp-heat exposure mainly due to a sharp decrease in the carrier mobility, while the carrier density and transparency degraded only partially. The increase in resistivity can be ascribed to a degradation of the structural properties of ZnO films, resulting in a higher level of tensile stress, as indicated by x-ray diffraction analysis, and in a reduced near-ultravoilet emission level in their photoluminescence spectra. Al2O3 thin (25–75 nm) films grown by spatial-ALD at 0.2 nm/s are used as moisture barrier to effectively enhance the stability of the electrical and structural properties of the films.

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Influence of damp heat on the optical and electrical properties of Al-doped zinc oxide

Cited by 39 publications

References 10 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

Synchrotron-based spectroscopy for the characterization of surfaces and interfaces in chalcopyrite thin-film solar cells

On the environmental stability of ZnO thin films by spatial atomic layer deposition

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