Role of Cu on the electrical properties of CdTe∕CdS solar cells: A cross-sectional conductive atomic force microscopy study

Moutinho, H. R.; Dhere, R. G.; Jiang, Chun‐Sheng; Gessert, T. A.; Duda, A.; Young, Matthew R.; Metzger, Wyatt K.; Al‐Jassim, M. M.

doi:10.1116/1.2699923

Cited by 18 publications

(13 citation statements)

References 18 publications

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“…Further considering that the density of Cu impurities in the poly-CdTe films is ~10 19 cm −3 and that they are inhomogenously distributed, it is probable that the required conditions for impurity band formation are met within certain high-concentration regions or connecting channels. This picture of impurity band conduction is supported by previous studies that link higher Cu concentrations near grain boundaries with higher conductivity 30 .…”

Section: Discussionsupporting

confidence: 81%

Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging

et al. 2013

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Thin-film polycrystalline semiconductors are currently at the forefront of inexpensive large-area solar cell and integrated circuit technologies because of their reduced processing and substrate selection constraints. Understanding the extent to which structural and electronic defects influence carrier transport in these materials is critical to controlling the optoelectronic properties, yet many measurement techniques are only capable of indirectly probing their effects. Here we apply a novel photoluminescence imaging technique to directly observe the low temperature diffusion of photocarriers through and across defect states in polycrystalline CdTe thin films. Our measurements show that an inhomogeneous distribution of localized defect states mediates long-range hole transport across multiple grain boundaries to locations exceeding 10 μm from the point of photogeneration. These results provide new insight into the key role deep trap states have in low temperature carrier transport in polycrystalline CdTe by revealing their propensity to act as networks for hopping conduction.

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Section: Discussionsupporting

confidence: 81%

Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging

et al. 2013

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“…Using Cu deposited onto CdTe films, it can by shown by XPS studies that a simple Cu overlayer is not formed, rather that the Cu, at least in part, diffuses into the substrate, with the formation of metallic Cd residues. [58] This interdiffusion, which is also evident in other investigations, [36,37,59,60] can be enhanced by increasing the substrate temperatures to about 300 8C. It is interesting to note that due to the temperature-activated interdiffusion, a change in the barrier height from the original pinning position of 0.9 eV above the valence-band maximum to a considerably lower value of 0.6 eV is also found, which is evidently related to the formation of Cu x Te y interface phases.…”

Section: Interface Engineering In Thin-film Solar Cells: Cdte Junctionssupporting

confidence: 50%

Interface Engineering of Inorganic Thin‐Film Solar Cells – Materials‐Science Challenges for Advanced Physical Concepts

2009

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The challenges and research needs for the interface engineering of thin‐film solar cells using inorganic‐compound semiconductors are discussed from a materials‐science point of view. It is, in principle, easily possible to define optimized device structures from physical considerations. However, to realize these structures, many materials' limitations must be overcome by complex processing strategies. In this paper, interface properties and growth morphology are discussed using CdTe solar cells as an example. The need for a better fundamental understanding of cause–effect relationships for improving thin‐film solar cells is emphasized.

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“…Previously, we prepared cross sections of CdTe/CdS using this method for conductive AFM (C-AFM) studies [8]. The GaAs cleaves easily, and more than 90% of the cleaved samples provide good AFM data.…”

Section: Experimental Methodsmentioning

confidence: 99%

Scanning Kelvin Probe Microscopy of CdTe Solar Cells Measured Under Different Bias Conditions

et al. 2009

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We have investigated different methods for preparing CdTe/CdS cross sections for electrical measurements, including the following: cleaving; using GaAs substrates; and sandwiching the structure between the substrate and a glass slide, and polishing with diamond discs and alumina suspension. The latter method proved to be the most reliable, with a success rate of over 90%.We investigated cross sections of CdTe/CdS samples with scanning Kelvin probe microscopy (SKPM) using two different methods: applying the alternate bias with a frequency equal to 18.5 kHz, or equal to the frequency of the second cantilever resonance peak. The results showed that using the second resonance frequency produced a smoother signal, allowing the calculation of the electric field inside the device using just the raw SKPM data.We were able to measure the distribution of the electrical potential inside working devices. Then, by taking the first derivative of the potential, we calculated the electric field and determined the location of the p-n junction.

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Role of Cu on the electrical properties of CdTe∕CdS solar cells: A cross-sectional conductive atomic force microscopy study

Abstract: Photoluminescence spectroscopy and decay time measurements of polycrystalline thin film CdTe/CdS solar cells

Cited by 18 publications

References 18 publications

Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging

Measuring long-range carrier diffusion across multiple grains in polycrystalline semiconductors by photoluminescence imaging

Interface Engineering of Inorganic Thin‐Film Solar Cells – Materials‐Science Challenges for Advanced Physical Concepts

Scanning Kelvin Probe Microscopy of CdTe Solar Cells Measured Under Different Bias Conditions

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