Microcrystalline thin-film solar cell deposition on moving substrates using a linear VHF-PECVD reactor and a cross-flow geometry

Flikweert, A.J.; Zimmermann, T.; Merdzhanova, Tsvetelina; Weigand, Daniel; Appenzeller, W.; Gordijn, A.

doi:10.1088/0022-3727/45/1/015101

Cited by 13 publications

(6 citation statements)

References 21 publications

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“…This efficiency is only slightly lower than that for a solar cell incorporating an optimized i-layer grown statically (constant growth conditions) at the same deposition rate. This observation indicates that changes in the local growth conditions can be tolerated to a certain degree in a dynamic deposition process which is in agreement with earlier findings [13]. For μc-Si solar cells incorporating ilayers grown statically by VHF-PECVD using linear plasma sources efficiencies of 7.7 % at a deposition rate of 1.4 nm/s have been obtained showing that further improvements for dynamic deposition processes are possible.…”

Section: Resultssupporting

confidence: 91%

High-Rate Deposition of Intrinsic a-Si:H and μc-Si:H Layers for Thin‑Film Silicon Solar Cells using a Dynamic Deposition Process

et al. 2012

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Thin-film silicon solar cells based on hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (μc-Si:H) absorber layers are typically deposited using static plasma-enhanced chemical vapor deposition (PECVD) processes. It has been found that the use of very-high frequencies (VHF) is beneficial for the material quality at high deposition rates when compared to radio-frequency (RF) processes. In the present work a dynamic VHF-PECVD technique using linear plasma sources is developed. The linear plasma sources facilitate the use of very-high excitation frequencies on large electrode areas without compromising on the homogeneity of the deposition process. It is shown that state-of-the-art a-Si:H and μc-Si:H single-junction solar cells can be deposited incorporating intrinsic layers grown dynamically by VHF-PECVD at 0.35 nm/s and 0.95 nm/s, respectively.

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Section: Resultssupporting

confidence: 91%

High-Rate Deposition of Intrinsic a-Si:H and μc-Si:H Layers for Thin‑Film Silicon Solar Cells using a Dynamic Deposition Process

et al. 2012

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“…Details of this process can be found elsewhere. 26,27 Sputtered ZnO:Al and silver were used as back contact. I-V measurements were performed in a class A sun simulator under AM1.5.…”

Section: Methodsmentioning

confidence: 99%

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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“…Since the µc-Si:H film formation was stopped before the X c growth increases, the continuous deposition time of µc-Si:H was shortened, and much of the amorphous phase easily formed [8]. Therefore, much of the amorphous phase increased V oc [3], and decreased I sc [33]. Since the shunt resistance was increased by the rising number of SEG, FF was decreased [34].…”

Section: Discussionmentioning

confidence: 99%

Intermittent Very High Frequency Plasma Deposition on Microcrystalline Silicon Solar Cells Enabling High Conversion Efficiency

et al. 2016

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Stopping the plasma-enhanced chemical vapor deposition (PECVD) once and maintaining the film in a vacuum for 30 s were performed. This was done several times during the formation of a film of i-layer microcrystalline silicon (µc-Si:H) used in thin-film silicon tandem solar cells. This process aimed to reduce defect regions which occur due to collision with neighboring grains as the film becomes thicker. As a result, high crystallinity (X c ) of µc-Si:H was obtained. Eventually, a solar cell using this process improved the conversion efficiency by 1.3% (0.14 points), compared with a normal-condition cell. In this paper, we propose an easy method to improve the conversion efficiency with PECVD.

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Microcrystalline thin-film solar cell deposition on moving substrates using a linear VHF-PECVD reactor and a cross-flow geometry

Cited by 13 publications

References 21 publications

High-Rate Deposition of Intrinsic a-Si:H and μc-Si:H Layers for Thin‑Film Silicon Solar Cells using a Dynamic Deposition Process

High-Rate Deposition of Intrinsic a-Si:H and μc-Si:H Layers for Thin‑Film Silicon Solar Cells using a Dynamic Deposition Process

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

Intermittent Very High Frequency Plasma Deposition on Microcrystalline Silicon Solar Cells Enabling High Conversion Efficiency

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