Extracting Cu diffusion parameters in polycrystalline CdTe

Akis, R.; Brinkman, Daniel; Sankin, Igor; Fang, Tong; Guo, Di; Vasileska, Dragica; Ringhofer, Christian

doi:10.1109/pvsc.2014.6925635

Cited by 13 publications

(6 citation statements)

References 12 publications

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“…That 1D solver in turn represented an extension to simulation work that looked at the problem of defect migration almost exclusively in terms of diffusion, omitting self-consistent field effects and reaction terms. [51][52][53] Simulation studies of defect diffusion along grain boundaries in 2D CdTe have previously been performed for the defect cases of Cu, 40 Cl, 54 and P, 55 using Fisher style models that were described in Section II B. These papers again omit the effects of reactions as well as self-consistent field effects.…”

Section: Discussionmentioning

confidence: 99%

“…40 The pure diffusion formulation has the advantage of being numerically more stable and leads to symmetric matrices, which result in a more efficient unconditionally stable implicit numerical scheme.…”

Section: Proposed Modelmentioning

confidence: 99%

“…40 In Figure 5, we show the 1D total copper concentration cross-sections for grain boundaries with artificial widths ranging from 1.56 nm to 100 nm. These results are all extremely similar, but the number of degrees of freedom varies from 2595 to 13541.…”

Section: -7mentioning

confidence: 99%

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Self-consistent simulation of CdTe solar cells with active defects

Brinkman

Guo

Akis

et al. 2015

Journal of Applied Physics

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We demonstrate a self-consistent numerical scheme for simulating an electronic device which contains active defects. As a specific case, we consider copper defects in cadmium telluride solar cells. The presence of copper has been shown experimentally to play a crucial role in predicting device performance. The primary source of this copper is migration away from the back contact during annealing, which likely occurs predominantly along grain boundaries. We introduce a mathematical scheme for simulating this effect in 2D and explain the numerical implementation of the system. Finally, we will give numerical results comparing our results to known 1D simulations to demonstrate the accuracy of the solver and then show results unique to the 2D case.

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Section: Discussionmentioning

confidence: 99%

Section: Proposed Modelmentioning

confidence: 99%

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Self-consistent simulation of CdTe solar cells with active defects

Brinkman

Guo

Akis

et al. 2015

Journal of Applied Physics

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“…Based on the parameters we extracted from the single-crystal anneal simulation, Cu anneal simulation was performed for standard poly-crystalline CdTe/CdS solar cells for 200 seconds and at 220 o C. Previous experiments suggest that the Cu concentration should be around 10 17 cm -3 in the CdTe layer due to grain-boundary-enhanced diffusions [17]. Since we are performing one-dimensional simulations, we believe that it is not worth to try matching the Cu profile without including grain boundary effects.…”

Section: (2) Metastable Behavior In Cdte Solar Cellsmentioning

confidence: 99%

Cu Migration and its Impact on the Metastable Behavior of CdTe Solar Cells

et al. 2015

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In this work, we report on development of one-dimensional reaction-diffusion simulator needed to understand the kinetics of Cu-related metastabilities observed in CdTe PV devices. Evolution of intrinsic and Cu-related defects in CdTe solar cells has been studied in time-space domain self-consistently with free carrier transport. Resulting device performance was simulated as a function of stress time, thus showing pronounced effect that the evolution of associated acceptor and donor states can cause on device characteristics. Although 1D simulation has intrinsic limitations when applied to poly-crystalline films, the results presented confirm the validity and the potential of the approach presented in better understanding of the performance and metastabilities of CdTe photovoltaic devices.

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“…Teeter et al modeled Cu migration in polycrystalline CdTe solar cells with different solubility limits and various diffusivities with a finite source [12]. An improved version of 2-D Fisher diffusion model that accounts for segregation at the grain boundary was developed for Cu in CdTe by Akis et al [13]. In all three works, some effective Cu diffusion processes were employed without atomistic mechanisms accompanying Cu diffusion.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Copper Migration in Single Crystal CdTe

Guo

Fang

Moore

et al. 2016

IEEE J. Photovoltaics

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Absorber material with high and stable p-type doping that does not impede free carrier lifetime is the key component enabling efficiency and stability improvements in thin-film CdTe technology. To better understand the compensation mechanism and the metastable effects related to Cu acceptors, the most common p-type dopant in CdTe, i.e., a detailed kinetic model describing the behavior of intrinsic and Cu-related defects in this material, has been developed and applied for the first time. Migration and reactions of these point defects in single crystal CdTe have been investigated by solving diffusion-reaction equations in the time-space domain self-consistently with free carrier transport. The simulation results supported by reasonable match to experimental data have shed light on the nature of limited Cu incorporation (also known as the Cu solubility limits) and Cu self-compensation during the annealing and cooling processes.

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Extracting Cu diffusion parameters in polycrystalline CdTe

Cited by 13 publications

References 12 publications

Self-consistent simulation of CdTe solar cells with active defects

Self-consistent simulation of CdTe solar cells with active defects

Cu Migration and its Impact on the Metastable Behavior of CdTe Solar Cells

Numerical Simulation of Copper Migration in Single Crystal CdTe

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